ToME: the Tales of Maj'Eyal

Changing the way that resistances stack with themselves from additive to multiplicative would bring it in line with some other effects, like all speeds, talent weapon damage/+damage%(type), saves/effect resistance, and defence/evasion. It would change the balance of the game by making single pieces of equipment with high resistances much more powerful than several pieces of weaker resist gear. It would also require the change of all +resist gear/talents to higher values, to compensate for the weaker stacking, and all +damage gear lower, for their stronger stacking. One benefit of this is steady returns for resistances at all levels, instead of steadily increasing ones as your resistances increase.

There have been threads about this, with nice graphics and everything... look around.

Ah found them the second time around, here and here. Nine pages of looking was a bit tedious, since I was using the search function for the wrong keywords. I think it could be a good idea, though it's half a year too late to open the debate.