May as well do it properly, with the bare 300mm as well. This is how large they are in the frame. And no, I won't be getting the 600 out tonight
EDIT... found a 600+1.4x shot for comparison, so now added to the scale line-up. In the past, when-ever I've been upgrading focal length on lenses, I was always keen to see direct comparison to see how much difference it makes, so maybe this will help others decide the worth of more focal length.