I know I'm just going to be throwing more armchair psychology into the mix, despite the fact that this is my field of study, but I'm inclined to agree. If anything, I would go a step further and say that the only possible working definition of sane that we've managed to come up with so far is equivalent to functional. (Cue the programming jokes) The definition of sane, if you try to pin it down any better than that, seems to become "I know its absence when I see it".
My current thinking is that there probably is some better version of sane than we're currently able to define or produce, but paradoxically it wouldn't last very long in current societies because it would be not at all functional in any of them.
But don't listen to me, I'm completely crazy. :)