If he liked coffee because of the taste or warmth, that would be useful, I agree. He apparently doesn't care about those, though, from what he says. Since he actually cares mostly about the caffeine, and since high levels of caffeine produce mood swings for him (and me), going off coffee would seem to be the solution he wants.

Personally, I'm willing to put up with the mood swings, since it's not so much really high and really low as really, really high and kinda low. :) But that's just me.