I'd like to draw attention once again to the last paragraph I put in my first post on the subject.
lil' old me said:
Lest you think this is a problem with the psionics rules, I'll point out that a Sorcerer or Bard could easily do the same thing with the Spell Knowledge feat. It works just as well for them too- it may not be quite as good as always knowing all spells, but it does mean that you can know any spell you want to know- and use it- as long as you have a few rounds to prepare.
Any spontaneous spellcaster-type, one who can cast any known spell without preparing it first, can do this. It's not psionics causing the problem, it's the spontaneity.
That said, thank you all for the responses; that was my knee-jerk reaction to the matter as well, but players being players they started to argue the other way. And honestly, their argument does have some merit (not from a game-balance POV, but from a game-world-consistency POV). Having an effect that's already in place, not requiring concentration to maintain, just plain vanish if the caster "forgets" it has far-reaching implications. For example, what if a character loses a level, but has a multiple-day-duration effect in place somewhere, like a
Dominate, and that happens to be the spell he's forced to lose with the lost level? What if the character "forgets"
Permanency, but still has some now-Permanent effects in place on itself? And perhaps most important of all, why don't the effects of Instantaneous spells that leave something in place (for example,
Flesh to Stone) reverse themselves?
Perhaps the ability to switch a feat with Anyfeat involves some sort of dipping into alternate realities. This would mean that the deity with the ability is able to keep itself in a sort of state of quantum flux, if you will pardon the brief dip into science jargon; anything is possible with it, but only one thing can be actualized at a time. If you switch the actualization, your new reality excludes whatever was done with the former one. However, this would still leave the problem of Instantaneous effects left in place (again, like
Flesh to Stone), but perhaps more careful thought can find a way around the problem.
In any case, I'd advocate that a special note be added to Anyfeat regarding this loophole; surely my players won't be the only ones who find it. Equinox's player is a powergamer, but he's not the type who hangs out on the Character Optimization boards at wizards.com- he'd never figure out Pun-Pun or any of the other absurd combinations that have been invented to defeat him. If he could think of this, plenty of others will.