You will notice a hell of a difference, thats for sure. I ordered the grip a couple months after I had baught the camera. I have used the 400mm F/2.8 L IS
(1 oz lighter than the 600mm F/4 L IS
) and the fairly heavy 300mm F/2.8 L IS
and I think it would have been really awkward shooting without the grip.
When I ordered the 20D, I included the BG
-E2 in the same order.
You will love it.