Sorcerers become pretty much obsolete with Psions available, since they are pretty much better at everything they can do.
Psions can burn through their power point reserve quickly, so you should challenge them with multiple tough encounters per day, so they have to divide their power expenditure and cannot just use it up to full degree all the time (every now and then is cool and fun, of course). That's similar to magic, where the same is true as well. If you only have one or two encounters per day, every spellcaster is much more powerful than he or she should be, especially at moderate to high levels. Psionic characters are even more extreme there, because of the added flexibility, which allows them to manifest tons of high level powers each day, if they can just waste their power points like crazy.
Dispel Psionics and the powers which increase save DC by +1 per PP spent (instead of 2 PP) should be changed as noted (every power should have the DC based on +1 DC / 2 PP spent on Augmentation, as that is a fundamental mechanic within the whole system, magic or psionic).
I'd change Dispel Psionics like this, which seems the most true to the general system:
For 5 PP you get a +5 check, which does not increase with your manifester level (like pretty much every other power in the book).
Augmentation: +1 PP for a +1 to the check. No upper limit as usual (thus it will be better than Greater Dispel eventually, but then again, there is Mordenkainen's Disjunction, which Psions do not have, so that seems fair enough).
I'd not allow Metamorphic Transfer as written (just use Assume Supernatural Ability from Savage Species instead, which is a lot more balanced). It's just plain broken that way, unless you put extreme limits on what forms are available with Metamorphosis (and similar polymorphing magic).
I think Schism and Quicken Power are too much, compared to the spellcasting rules, where this stuff has been removed in 3.5, or was never available (spontaneous casting (manifesting) and quicken). So I'd be a bit wary of that stuff. You can also go the other way, of course, by allowing Quicken Spell to be used spontaneously without any limits and adding a new 4th level (personal) arcane spell, with a duration of 1 round per level, which gives one extra standard action per round.
Hustle is not really a big problem, but it can cause some, since it is a key element to some combos, especially for Psychic Warriors, which basically circumvent the cost of many psionics feats (psionic focus), which have this cost, since they are otherwise simply better than general feats. I believe it's better to move Hustle to 1st level and change it to add 30 ft. base move instead of an extra move action. But as I said, this is not really that important.
Overchannel/Talented is a problem as well, because it not only allows you to raise your manifester level, which is fine by itself, but since psionics have no fixed power level, it also indirectly allows you to manifest powers of a level higher than you have available. Kinda like if a wizard could cast 9th level spells at 14th character level already. Sure, you do not have any 9th level powers yet, but many of the lower level powers have augmentation, which effectively makes them 9th level (or higher than their actual level) powers. Dominate is one example. Dominate Monster is a 9th level spell (would be 8th level for a Telepath then, I think) and would be available when you only have 6th - 7th level powers still, which is way too early, of course. Now, this example is pretty dumb, since Psionic Dominate is a 4th level power and thus cannot be used with Overchannel/Talented (only up to 3rd level), but the general idea is there. Take Astral Construct for example, that should work fine here, or any of those "modular" powers, which include the greater versions and are 1st to 3rd level at the base.
There's a lot more than that, but this is the most obvious stuff, I think.
In general, if your player is cool with that, I'd just look for any problems which arise during play and find a solution afterwards. If a problem exists, but does not apply to your campaign, there is no real need to think about it. Just tell him, that you are not that experienced with the psionic rules and therefore will maybe have to make some judgement calls or retroactive changes during the game. If that is not a problem for him, it should work fine, I guess.
Bye
Thanee