LOL! The Canon salesmen are out today!
I'd try
www.nikonians.org and ask there. It's a dedicated Nikon forum and is simply HUGE. There are lots of astrophotographers there to ask your questions of. Great to have another Nikon devotee aboard! Welcome!
On the flip side... I've heard that Canons have managed to improve over time, and that they actually do OK for themselves in astrophotography circles these days. 