Steve, welcome. You haven't given any details about this "desired location" downstairs for the new receiver, but it doesn't seem to be a good idea to be looking for a smaller receiver rather than looking for enough room for the receiver that you want. It also wouldn't seem to be wise to consider removing the feet to save 1/2" or so if this results in blocking the ventilation slots on the bottom.
The Axioms that you'll get will sound good with any receiver in the category that you're considering and a few watts one way or the other are meaningless. If you're still going to insist on a smaller receiver it can be mentioned that the Denon 4310 is smaller and lighter(about 1" lower and 34 vs 54 lbs)than the 906.
