got a player who wants to play one but is really hung up on psionics should be int based.  he says no intent to multiclass so we can rule out interactions there. from what i can see it would change his save prof from cha to int, his spell to hit bonus and dc to int, careful and empowered metas would be int not cha, telepathic speech's range would be int based.  nothing seems bad here. anything else i'm missing? i'm not even sure multiclassing would be bad, but i don't have to worry about it at all.  

i've tried explaining he can just roleplay it as smart but he is really hung up on the int vs cha thing and i'm pretty tempted to let him.  just looking for anything that is likely to bite me in the future

You've pretty much covered all of the bases with the basics that would be changed and anything you forgot you can easily catch as the character is made or as play goes along.  So really with the thought that it's a home brew alteration you can certainly go ahead and do it.

The only major difference not covered would be that he'd be better at Arcana checks than the CHA-sorcerer, and less socially adept. Which is a fair trade off.

The INT bonus thing is probably tied back to the fact that psions are traditionally an INT class; I've actually thought the same thing, allowing INT based A.B.'s for that reason.

I firmly believe in: Rule 1) Its your world, your campaign, your call as DM.

But just to point out psionic/psychic ability has nothing to do with intelligence, best two examples of that that spring to mind are:

Eleven - The young girl from Stranger Things
Carrie - For those that prefer their horror

From the Forgotten Realms Wiki:

"A psionicist is a person who uses the power of the mind, or psionics to influence objects, rather than magic. Often colloquially referred to as "mind mages," they draw their powers from their own consciousness using methods that must be replenished, or can be innate, as in illithid and drow practitioners. Although it is not fully known, this gift is an inherited trait and is subsequently genetic"

Nothing to do with intelligence. That said there are those that do gain it through study & meditation, which you could also use to argue for Wisdom at the stat (High level monk/priest)

That said, refer to rule 1 :)

I think you've covered any possible 'power-up' by not allowing multi-classing.

Note:

Apart from level 1 there is nothing really Psionic about the AbSoul's features until lvl 14. Is there some reason they don't want to play a wizard with the Telepathic Feat? If you like his backstory you could even give him the ability for free @ lvl 1, if he wants to play a wizard sub-class as Psionic (I.e Divination).

I don't think there is anything powergamey that can be done here.

The only thing I'd consider is if there is a wizard or artificer in the party and if they are going to feel like their role for the int based stuff is being stepped on.

I do think he's missing a huge RP hook with being able to jedi mind trick everyone into doing what he wants with psionics and CHA rolls.  IMO charisma is a much more fitting stat for this subclass unless he's putting his own spin on it.

Quote from Bodanger >>

I don't think there is anything powergamey that can be done here.

The only thing I'd consider is if there is a wizard or artificer in the party and if they are going to feel like their role for the int based stuff is being stepped on.

 Would they feel that way if there was a wizard and an artificer in the party?  I'm not really seeing the issue.