Regarding changes to Psi, I think it'd also be cool if psionic enemies had full access to psi abilities just like the player does. Unique psi enemies, or high level ones on DOMINATING could use implosion, or throw a cryokinetic orb at you if you're not careful (seeing them occasionally miss horribly and kill themselves and their allies would also be hilarious). Enemy psi monks could use force emission with a pair of steel gloves, and cast force field to either enable their escape, or prevent yours. Rare enemies specializing in temporal manipulation wouldn't be a huge direct threat on their own, but could empower their allies to devastating effect by casting psi haste on them, or dominate you by defbuffing you with psi slow, or by casting entropic recurrence on you right after his sniper buddy shot you in the face.
A change to force field would probably be in order as well, perhaps by giving each individual block of the force field its own HP bar and allowing it to be destroyed? The HP of each block could scale with the caster's effective psychokinesis skill, and could be further improved by the force user feat, which could give force field more HP rather than increasing duration. You could compensate for this change by increasing the total duration of force field by a turn or two.
I think the general idea should be to change boring, un-interactive and abusable stuff like force field and Thermo-D while still allowing Psi to be highly powerful - just not game breakingly so.
