Hi Denis, i work with a 40D and a 1Ds Mark III.
I use the 40 D because it is very fast and the lenses work different as with a fullframe body of the 1ds mark III.
The imagequality is fantastic AND the camera is weathersealed!!!! (thats the difference to the 400 and 450).
For a landscape photographer a good thing ((:
Here is a fantastic article and website for CANON equipment/comparing with each other
i have the camera myself, worth buying. although if you were considering, the 17-85 lens that comes with it is fantastic if the kit crossed you’re mind.