The belt is the reason why i'd go to the temple asap with a gadgeteer. It's even the main reason why i prefer a gadgeteer over a bard. Superman doesn't only boost abilities, but stamina and hp, even sp (all due to the stat increases i'd say). Another plus is the fact that you learn skills faster (stat increase/more swings/attacks).
My current party casts Superman almost every fight (but then again it's a male solo pure bishop
no non-bishop level, no help. ) For a solo it's among the most powerful spells imho (together with guardian angel that is, heh).
Oh just one thing: I died once when superman ran out. I don't think the (additional) hp are subtracted, only multiplied, but they can be rounded down (eventually to 0). [img]tongue.gif[/img]