Hi edub,
I wonder - is it not enough to do the panning and zooming in the viewport instead of directly in the VFB? Or is it suboptimal for some reason?
If I may, I think it comes in handy when you are working from a specific angle and don't want to go out of your current camera just to "zoom in" to see the materials up close.
If I recall correctly this was a feature request for the core team a while back. The whole Real Zoom thing I think started with F-Storm and then V-Ray took up on it so... It is only natural we request it here as well lol :P
edit: Oh and its a +1 from me btw. That being said I do like the current behavior of the IR doing only region renders if you zoom in. Could be introduced as additional functionality when you right click in the VFB with the pick functionality - Similarly as we do focus distance etc now. In fact, thats how V-Ray does it too lol.