To be honest, I don't think you should switch to Nikon.
Save your money up for a bit longer, and think of upgrading to EOS 1D4 body. In Australia, those are down around AUD$4200, and it's a heck of a lot of camera for the money, with brilliant AF and great low light performance. It's also really, really fast.
I think a 1dmk4 is a great option, but it's almost 4X what my camera body costs alone. I think thats a little ambitious. If I have to buy a 4k dollar Canon body in order to get good AF and low light performance. Buy selling 3 items. I know a guy who sold 24-70L 70-200 f/2.8L IS II, 50L, 50 f/1.4, 430 EXII, 580 EXII, 100 Macro, 5dmkii, and t2i inorder to buy a d3s, 16-35 f/4 VR, 24-70, and 70-200 VR II. WHY?
Nikon's AF and low light performance out does Canon every day of the week. As well Nikon Zooms are quite amazing now compared to the meh, 24-70 and 16-35. Not to mention Nikon's new prime additions with G lenses.
Is it a hassle, yes? But is it worth it for the long run. I think so, but as of now 9 AF points that do nothing but make me switch to manual focus in low light ain't doing much for me. So I'll take a hassle and in the long run enjoy a company that seems to know what its customers care about.