Well David, one good outcome of this thread/conversation . I went out for birds this AM. I took the D300s/500vr w/tc 1.4 and the D3S/300 2.8vr w/tc1.7. When I arrrive in my jeep I normally take the D3S walkabout for the early light and handheld to see if it is worth setting up the big lens.
With the D3S and distances I decided to play with the DX and 1.2 crops. Works fine and the file sizes are a treat since I normally have to crop the heck out of the shots anyway, and still did . Cheers, Tom