AbdulAlhazred
Legend
Actually, it's more likely to give you +6 to +7 at 11th, but I won't try to argue if the OP board guys have determined that a mage pyro deals more damage. I'm still doubtful, but they tend to be right about such things.
Maybe my knowledge of charops is outdated? Last I knew Genasi Firesoul Pyromancer Mage was winning that contest flat out. I'm not sure where +6 or +7 at 11th comes from, you could start with an 18 in your secondary stat I suppose but there are nice optimizations for Mages as well, less costly ones that open up more Paragon level feats. I think that's where the difference is.