I think the Saints offense will be too much for the 49'ers to handle. SF always seems to give up a couple of big passing plays per game. Against NO, expect them to give up 4-5 big ones and not be able to stop the passing game. They just don't have a good secondary, nor great pass rushers outside of Aldon Smith. And having Alex Smith at QB, as much as he's improved and cut down on mistakes, is still like bringing a pea-shooter to a gun fight.
As a 9'er fan, I hope I'm wrong, but I see NO winning big, just like they did against Detroit.