I took the plunge and traded in my 400D for one of these (plus my 60mm macro lens, as it no longer fits
)
I've not had much chance to play around with it yet, but from what I've seen so far its an awesome camera. A HUGE step up from my old one. Its so weird seeing my 24-105mm L lens on the FF sensor and how much more you get in frame.
So far, well worth the money and an easy choice over Nikons D700.