Whatever he asks, I think he'd mostly deserve it. I imagine you saw that TD catch he had, Brees threw it high and behind him.. and he still stopped, twisted back and caught it... the 49ers need guys who can do that.
While Aldon obviously and deservedly gets most credit for his pass rushing, he's done a nice job against the run this year. He's got the potential to be a really good, complete player in a couple years. Not sure he'll ever be great in coverage, but I can live with that.