Hey great thread.
I'm curious about how adapting full frame lenses influences compression, if at all. I know a Nikon 300mm f/4.5 NIKKOR-ED Ai-S IF will have the same angle of view as a 450mm lens. It won't have the same DOF as on full frame, it will effectively be an f/6.75. This leads me to doubt that compression of the lens is influenced at all by use with a different sensor size. There's also subject isolation, which may or may not be the same thing?
I spend more time taking photos than thinking about these things, so don't worry. Help me understand. Heh.
