So the Vigilante looks like a fun addition to the base class collection. With all of the great options that could come out with Ultimate Intrigue, there might be a fun and useful niche for a character, and especially for a villain, that can legitimately be two people. I know I'm super excited to get my hands on all of the Intrigue options for Eberron stuff (I've always loved its gumshoe/Indiana Jones vibes), and potentially even run a campaign full of Slayers, Investigators, Alchemists, and Vigilantes. That said, Vigilante has--ironically enough--an identity problem. It wants to be everything and, as is usually the case with this kind of design, it ends up being not much.
Since this is a playtest, I've rolled up a few Vigilantes and run them through scenarios I've used in the past from Curse of the Crimson Throne, Eyes of the Lich Queen, and a bunch of other little modules and my own little adventures I've run over the years that have focused on both intrigue or mysteries and combat. They were fun, and lent themselves to really cool and interesting role-playing stuff, but there were some issues, especially with combat and feeling like, in some cases, I'd be better off playing a character that was fluffed as a vigilante with two identities, rather than actually being a Vigilante.
First off, I think that Avenger and Stalker ought to be combined into one pool of talents, if we're sold on having distinct pools. I'm also not thrilled about Hidden Strikes (it's a really pretty terrible Sneak Attack, and Sneak Attack already isn't great, not to mention that a base class is getting a worse version of another base class's defining ability), but having the option of picking either full-BAB or something equally impressive for a more skill-based side at level 1 would be great. Honestly, I'd love to see something sort of similar to Investigator Inspiration, a pool that lets the Avenger (the better name for the combined talent pool, I think) use pool points to gain an edge in both combat and social encounters. Something like spending a point to gain a +1d4 to a set selection of skills, chosen at creation and able to be expanded with Skill Focus or talents, and maybe a +level bonus on damage by spending a point, a little like a Swashbuckler's precise strike. That's a bit more complicated than I think the class needs, though.
Keeping Hidden Strikes wouldn't be the end of the world, and I have to say there are some fun options that play off it; I just hate the whole "unawares" thing. It really should be fixed to having an effect whenever an opponent is effected by a "negative condition", or anything that adversely affects them, and be a small static damage boost and allow for the Vigilante to deal nonlethal without penalty whenever they can get their ability off. So if an opponent is, say, flanked, the Vigilante's Hidden Strikes give a scaling +1 hit and damage bonus (+2 at 3rd, +3 at 5th, etc.). If they're blind or flat-footed the same would apply, and likewise with sickened, prone, nauseated, fatigued, bleeding, etc. It's a small boost, but it would leave spikes of damage to the rogue while also giving the Vigilante that picks this option the feel of taking advantage of every little weakness offered to them. It could look like this:
Hidden Strikes (Ex):
Starting at 1st level, the avenger vigilante gains +1 on attacks and +1 precision damage on melee attacks (or ranged attacks within 30 feet) against foes who are flanked or affected by a negative condition (such as flat-footed, sickened, or fatigued). These bonuses increase by +1 at 3rd level and every 2 vigilante levels thereafter. Additionally, whenever the avenger vigilante is granted these bonuses against an opponent, he/she may choose to deal nonlethal damage to that creature at no penalty.
I think this combination of features would lend itself to more nuance in builds, more interesting and diverse options, and a character that's more effective as a character. As is an Avenger is a worse Slayer, and a Stalker is a worse Rogue, not counting what could potentially come for the social side. Still, it boils down to the combat half being a much less effective combatant than its obvious parallel, and both a Slayer and a Rogue have baked-in potential for exceptional use outside of combat with skills. And when a majority of people build Pathfinder characters, they build for combat effectiveness, or at least build with combat in mind. Nobody wants to or likes to be dead weight in fighting encounters, even if they're a skill god.
Second, I think Warlock and Zealot should be combined as well, with the option to pick either the arcane or divine spellcasting talent from the get-go as the base. Just call this one Warlock. Here's actually where I think the class can find a pretty great identity; if we allow the player to use their talents (and let them have Extra Talents, yeesh...) to pick up both arcane and divine casting, the class has baked-in mystic theurge abilities. To keep from being too powerful, the character would just need to use the same number of spell slots and spells per day for both types of casting. Perhaps allow for higher level talents to grant bonus spells/day to lower levels (so Arcane II would give an extra spell slot, not stacking with Divine II), and then you've got a pretty interesting and fun base class niche. If not, then Zealot should just be removed. I hate feeling like I'm belittling or not appreciating the time and effort it took to put out that content, but Zealot wants to do Inquisitor, and Inquisitor does Inquisitor better than Zealot ever could. And, what's more, if Zealot were a better Inquisitor, then what's the point of having the class? They're too similar as base classes, and since Inquisitor isn't a hybrid (why I'm ok with Vigilante being a little similar to Slayer or Investigator) you're just making two classes that are trying to use the same mechanics for the same ends, and one is drastically better at it than the other.
I think having a class with two base options like this could be pretty fun, on top of the (seemingly minor) social and flavor stuff that the alternate identity gives. On the one hand you've got a character who can choose to avoid armor check penalties and can break through doors while chasing down his mark, while also having the ability to case a joint and jab spellcasters in the throat with either small situational bonuses that open up more special attacks and damge, or constant full BAB that allows for more feat options and consistent accuracy. On the other hand you've got a character that could be an arcane caster with a domain, or a divine caster with a familiar, or both, while also having the ability to hide his magical meddling as Sir Walter Wunderberger. His spellcasting might be relatively minor or limited, but talents give more interesting build options than a bard or inquisitor and also lets the character effectively "dip" into mystic theurge; if you only want to get to level 2 divine spells or arcane spells, you can stop taking the talents any time in favor of other options. Seems pretty cool to me.
On the topic of Sir Walter Wunderberger, I do love the alternate identity. It's fun, and really something that I like for Eberron intrigue with Dragonmarked houses, spies from different nations, and having a vigilante and social persona that are each moonlighting as each other. That said, the switch time is too long. It ought to be rounds, not minutes, since unlike Disguise you can only turn into one other person, and switching between the two is a basic part of the character's personality, not just some random person they suddenly decided to be (except for the "mundane" persona, but still; you aren't a specific person then either, so you can't step on Disguise's toes there either). Besides, if Sir Walter and The Reprimander both constantly turn up within a block of one another (but never in the same room), suspicions will be raised; no reason to make it difficult to be both sides. That said, too, all of the character's skills should be available to them at all times. Batman doesn't forget he's Batman, Superman doesn't stop being Superman, they both just try to avoid using their abilities when they aren't in costume. The only caveat should be that using a Vigilante combat ability as the social persona should have the potential to cue off the link between identities, and likewise if Reprimander starts talking about Sir Walter's fishing empire as if it's his own, well... It means that the character can always operate at full effectiveness, but they have to be careful which abilities they use or how they use them if they want to maintain the two identities as separate people. And if Sir Walter is actually Prior Walter and is a priest by day, while Reprimander has a reputation for fireballs by night, then that kind of flavor should be mechanically feasible and encouraged; the player should pick how these abilities manifest themselves, and work with the DM to talk about how much they can do in the social persona before things start getting fishy.
Talents themselves and class abilities can always be fiddled with, but I think having two paths instead of four and making sure that the player isn't punished or mechanically disadvantaged for having two identities (what should be the real appeal of the class) is important to make sure that the class actually has an identity. That, and I think there's actually an opportunity here to make something that I know I've been wanting for a while, a "base" Mystic Theurge, while also giving the Avenger options a great suite of customizability to make the hero you want and the hero you deserve.
TL;DR:
- Combine Avenger and Stalker, Warlock and Zealot (or remove Zealot).
- Make Hidden Strikes not a bad and narrow Sneak Attack ripoff.
- Reduce the identity switches to rounds, not minutes.
- Allow for all abilities to be usable at all times, with the risk that using either identity's abilities could/should result in blowing your cover.
Your main point of combining the two martials and casters has been something myself and friends have discussed and seems to be the best way to deal with the class.
I do think though that if done, they can leave hidden strike how it is.
Switching takes too long, everyone knows that.
I don't think all things should be usable all the time, but it does seem silly that my stalker could get thrown out a window in his social mode and fall to his death when he has perfect fall.