Theurgic Adept - dual-progression prestige for 6 / 9 casters

After looking at the Arcane Hierophant from 3.5, I was inspired to design a theurge prestige class for divine and arcane casters that normally top out at 6th level spells (6/9 casters). Here's the initial version of the Theurgic Adept:

Google docs

Short summary:
7th level entry for characters with either 3 Hunter, Inquisitor, or Warpriest AND either 3 Magus, Bard, or Skald.
12 total levels (for now)
d8, 0.75/lvl BAB, 0.5/lvl F, 0.33/lvl R, 0.5/lvl W
Dual progression in divine and arcane spells, always one spell-level behind from lvls 4-18. 6/5 at lvl 19, 6/6 at lvl 20 if you go back to base classes after lvl 18.
Certain base abilities of the entry classes advance as levels in theurgic adept are taken. Language encourages GMs to consider replacing those abilities to match that of archetypes taken.
Companion Familiar similar to that from Arcane Hierophant; gained iff character had both animal companion and familiar from class features.

Guidelines/paradigms I thought about while designing:

• 6/9 casters are unfit for traditional theurge prestige classes; they rely on class abilities more than 9/9 casters.
  
• Depending on their power, I usually chose two class features to advance with theurgic adept. One tended to advance completely while the other advanced without gaining extra features. E.g., theurgic adept levels may stack with magus level for arcane pool and for the effect of magus arcana, but they do not stack with magus level for feating for new arcana. Also e.g. theurgic adept levels may count as effective druid level for hunter's animal companion and may stack with hunter levels for animal focus, but they do not grant a second animal focus.
  
• I love flexibility, but the best I could do for archetypes was say "GM may approve" of swapping out class abilities advanced by theurgic adept.
  
• Still regarding flexibility, I wanted to say something about like "pick two arcane class features and two divine class features and stack your theurgic adept levels for them" to allow for both archetype and homebrew flexibility for folks, but that's too hard to balance even when limited to just 6/9 caster classes.
  
• Companion familiar from Arcane Hierophant is like my favorite thing, and animal companions need help at higher levels anyway.

Considering that there's no early entry (and thus slow spell progression and an early-level hump), only 12 levels in the class, and prestige-class-trash saves (edit: and MAD), I hope that balances out having certain features from a couple classes advance along with dual spell disciplines. I can always tweak the entry level and/or prestige max levels to buff the class. Conversely, I can drop some class abilities if folks think it needs nerfing.

Thanks for reading, y'all. I won't presume to ask you to test it, but how do you think it looks as a theurge option for Pathfinder's existing gish classes?

Wild -- first time I have looked at a Google Docs document while somebody was in progress at editing it -- saw a moving pink cursor and stuff changing before my eyes.

Anyway, I think you could put Summoner in there. Theurgic Adept would progress spellcasting, the Summon Monster SLA, and Eidolon, but Eidolon progression would be with respect to Hit Dice, total Evolution Points, and other things on the Eidolon table, but not with respect to what Evolutions the Eidolon could qualify for (that is, for any Evolution that says you need Summoner Level {whatever} to qualify for it, that is, you only count actual Summoner levels).

Main aggravation is that every time a new 6/9 spellcaster is added, you have to update this prestige class, but unfortunately that seems to be unavoidable.

Wild -- first time I have looked at a Google Docs document while somebody was in progress at editing it -- saw a moving pink cursor and stuff changing before my eyes.

Anyway, I think you could put Summoner in there. Theurgic Adept would progress spellcasting, the Summon Monster SLA, and Eidolon, but Eidolon progression would be with respect to Hit Dice, total Evolution Points, and other things on the Eidolon table, but not with respect to what Evolutions the Eidolon could qualify for (that is, for anything that says you need Summoner Level {whatever} to qualify for it, that is, you only count actual Summoner levels).

I wasn't doing that to give you a seizure I swear! I might put that particular text aside in a box to clean up the rules.

Thanks! I totally forgot about Summoner when I set out to actually get this done. Your suggestion will be the jumping off point when I revisit today or tomorrow. Luckily that still works for Arcane Armor Training, though I guess it's well enough a summoner will not qualify for companion familiar (without some more multiclassing; not sure I'd that's worth shutting down).

Seems a nice idea and I'm definitely interested. Minor thing- I don't think you explicitly say how the stats of the familiar and the companion interact. If the int becomes that of a familiar, as I suspect, that could be restated just in case. Apart from that, love the class!

I want to tread lightly with the Summoner to make sure it's not OP to advance those class features, but I'm just not as familiar with that class as I ought to be. That said, seems that UnArcaneElection's suggestion of locking acquisition of higher-level evolutions would have the benefit of keeping all the bells&whistles with the pure Summoner, leaving this theurgic adept summoner with a still-functional buddy.

Occult origins has an Occultist archetype with divine spells, so I plan on looking into that class too.

Seems a nice idea and I'm definitely interested. Minor thing- I don't think you explicitly say how the stats of the familiar and the companion interact. If the int becomes that of a familiar, as I suspect, that could be restated just in case. Apart from that, love the class!

Thanks and good call. I made it more explicit that the familiar's intelligence bonus was added instead of his intelligence. Also there's an example in a tooltip that I hope will answer more questions than it'll invite.