No downside?, come now Kumu do you really think we are that stupid to think that Multiclassing has no downside? a 2x100 with absolutely no other classes has an adventure rating of 111... if you add a 3rd 100 then their adventure rating becomes 122... but there is no down side is there?... other than at 120+ you are getting cr*p for exp from anything less than 85. If the game is so utterly broken to you then quit, stuff a sock in it, or make reasonable logical suggestions for its fixing... continued whining and moaning does NOT win you any supporters to your cause nor does it endear you to AE nor any potential supporters.
Nuf Said!