My wonderful friend Jodi let me borrow her Nikon D700 and 105mm micro lens at Longwood on Saturday. It was really fun to play around with a new system. Honestly if I had the money I would probably keep both a Canon and Nikon full frame camera, and lenses.
Overall I would say I could be really happy with either system. I didn't find the Nikon easier to use, but I also think it wouldn't take me long to get the controls down. That camera body/lens combo did weigh a bit more than the Canon equivalent.