well the current average for hats is like 200-300 polys each i'm guessing, so a remodel or replacement would be possible, but to add player-made-hats and things, it'd need a complete overhaul. possible, but don't expect it too soon.
Also, I wish there was some way that prevents male faces from being selected when the female chest is chosen. It always irks me when people have female chests simply because they think they're "thin" chests.
I joined a server once that had the hatmod+ and lot's of players wearing hats, no lag after all