Thank you for the replies. I will be using in on 12x20, dont have the camera yet. Slowly buidling the bank account and gathering supplies.
I have both the Nikon 450mm and the Fujinon 450mm CMW sitting here (on loan from friends). I have been playing with both on 8x10 and over all prefer the Fujinon, (I use mostly Fujinon glass anyway and prefer them). My only worry is if it will cover when stopped down like the Nikon will. Not having the camera yet, I have no way of testing it.