Velmont raises a good point: Psions get more pp/day than psychic warriors, and thus psychic warriors stand to benefit more (percentage-wise) from this feat.
The same goes for Improved Toughness: A wizard has 1d4 hp/level, a barbarian has 1d12, so the wizard benefits three times as much from the feat (percentage-wise).
To be honest, I'm liking both feats (Psionic Reserve and Improved Toughness) less and less as I think about them. They have little flavor, and for Psionic Rserve, (like I said with Someone's proposal) I feel like you could improve your casting capacity with feats that already exist. Also, both of them mess with the fundamental progression of classes. Psion's pp/day were thought out carefully by the Wizards designers. And hit point progression was carefully planned as well. Now that I really think about it, this kind of feat subtly messes with the core of the game, and I don't like it. I'm starting to see why they made Toughness is so terrible.
And a comment on the flavor of this proposal and all proposals: I think our goal for LEW should be to keep the rules simple and the flavor strong. Less crunch, more fluff. My initial response to Someone's proposal was negative, but now that I see the flavor coming out, it's growing on me. I'd like to see more PrC's like "Collegiate Scholar of Nobius" and "Dervish of Sairundan". I'd like to see more feats like the Delmontes Technique chain, like "Psions can tap into the Towers to augment their powers" and "Spellcasters can use their own bodies as small "Towers" to increase their spellcasting power". I think that kind of thing gives Enworld a life of its own, a unique identity separate from other campaigns. Rules like this one that just mess with the basics should be scrutinized and considered at length, because passing them means we, as a community, believe that Wizards was wrong in balancing the game as it is.
Sorry for doing such a 180o on this. :\
