Shaman are Wisdom based. Only a select few abilities of theirs use Charisma, and unfortunately, most of them are spirit powers.
The archetype is no weaker than a Shaman, which needs mostly Wisdom with a non-dumped Charisma for some of their spirit powers. I see no reason you need to change this archetype.
Personally, I think the Shaman class is awesome and one of my top 5 favorite classes. The spirit powers and a rare few hex durations are the only things that use Charisma, so, there's nothing wrong with the way the Shaman is built.
Here's the breakdown by Spirit:
Battle uses Charisma for uses per day of base, Greater, and True spirit abilities. However, it's probably the second least useful Spirit for a Wizard anyway.
Bones uses Wisdom for the DC of it's Greater ability and only uses Charisma for the uses per day of its crappy Touch of the Grave that you'll have little incentive to use.
Flame, Stone, Waves, and Wind, which all follow the same pattern, use Charisma for uses per day of their crappy touch attacks, but they use Wisdom for the DC of their Greater abilities and no stats for their True abilities.
Heavens uses Charisma only to determine uses per day for its crappy (sensing a theme here?) base spirit ability, uses no ability for its greater, and needs Wisdom for the DC of its True spirit SLAs.
Life uses Charisma for Channeling and its True Spirit ability, which is admittedly a pretty strong reason to have some Charisma, but the Greater spirit ability uses no stat (and is garbage anyway).
Lore uses Charisma for uses per day of its basic ability (which is awful because it's a standard action), and then no stat for the other abilities.
Mammoth weirdly uses Charisma for the DC of is basic ability and its uses per day, which is a shame, because it's pretty good, but well, not for a Wizard, so that's not too big a deal. The other two powers use no stat, but, yeah, everything but the pet is crappy for a Wizard anyway.
Nature uses Charisma for uses per day for its junky basic ability, then no stat for anything else.
So, no, I don't think the archetype needs a change, I don't think the Shaman is poorly done, and I don't think you especially need Charisma unless you want a lousy-for-a-wizard Spirit or the Life Spirit, which, well, that's the price you pay, just like the Cleric.
Switching the Wisdom for Intelligence does help a few spirits, but, remember, they're not necessarily done printing spirits, so, the clause is there for the future, too, when more spirits might use Wisdom for more things.
This is getting slightly off topic but I guess I don't see why a class that is a hybrid of a CHA based caster (Oracle) and an INT based caster (Witch) was decided to be a WIS based caster but one that uses CHA for key things like the number of uses of 1st level abilities.
It is also Hexes. Most of the Shaman's hexes (not associated with spirits) use Wisdom if they use a stat for anything. While many (but not all) of the hexes from spirits that use a stat for number of uses, durations etc use Chrisma.
It just seems like they should have been consistent instead of some abilities using Wis and others (of the same type - ie hexes) using CHA.
I think they went with Wisdom because all of the other non-spontaneous divine casters use Wisdom for casting spells. In that sense it is consistent.
Spirit Whisperers are fun. It's nice that they can get Improve Familiar even though Shaman's can't.
And for a Spirit Whisperer, I love the Air Barrier Hex from the Wind Spirit. It is effectively mage armor that can be broken up into 1 hour increments, scales to +12, and eventually grants a miss chance for ranged attacks (including rays)! It is much more valuable to a Wizard than it is to a Shaman. The whole suite of Wind Spirit abilities is great for a Sylph Spirit Whisperer.
It does say that you use your intelligence modifier in place of your wisdom modifier for (THESE abilities)
I read that as abilities grants you use the intelligence modifier
Is that wrong?