I recently rented the Nikon 70-200 f2.8 VRII lens for a trip to Rwanda and it was fantastic. I'm back to my 70-300 VR and unfortunately it doesn't come close. I've had some great images out of it, but the F2.8 is something else. So, I'm considering buying one but there's the F4 as well, which is significanly cheaper. Has anyone here got or used both to give a comparison and pros and cons of either? I'm going to try and test the F4 this weekend hopefully. Also, any good deals on these out there at the moment? I'm seeing £1579 for the F2.8 and £850 for the F4. Anything better or with cash back?