are heavy casters (i.e. a fighter with full int) at a huge disadvantage when it comes to welling?

i've yet to hit lvl 64+ on a character, so i'm not sure if a char with ~4k mana would be able to beat a well boss

is mana usually what determines the outcome of a well battle for mages?

More mana means you can make battles last much longer. you can hack away for longer, and heal yourself more too.

mages get SO much more mana, and that's vital. I can turn 135 of my mana into ~400hp, and i'm using a pretty crappy heal charm.

A heavy caster would be good on hardcore where you need more life to lessen the chance of getting 1-hitted, but on softcore i personally dont see the point.

but you also gotta realize, you will be wearing heavy plates, so you will be taking alot less damage :). I think they do fine welling if you have decent gear