Originally Posted by Weebl
Shitty on a 40D, I need to buy another body but I'm a...
I can manual focus better than the 40D for absolute sharpness. On a 50/60/7/5D it should be better. Well worth the price of admission but it depends on what you shoot. I went with prime vs. 70-200 only because I would use it for birds and jets ( hit Maverics once). I have only regretted not going 70-200 a few times.Pop a 1.4x on and it is still good.
I don't know what wastegate rattle sounds like but the 300 F4 IS sounds like it would be comparable. From what I understand, that is normal.
I think your best bet since you say wildlife would be to aim for the 7D, it has a much faster auto focus then anything else you listed, and it's also sharper then the 5D mk II when cropped to 100%, so even if you're shooting off into the distance, you can zoom in a ton and nobody would know it was a crop. Yes the 5D mk II is good for that too, but you'd only want to crop to about 95% of the zoom since after that, things start to get a bit soft.
I have both cameras and have played with this crop ratio, and it's interesting to see the difference. That being said, if you're shooting wildlife in the woods or something and you need to use an ISO higher then about 640, then the 5D mk II might be the better option for you, although you sacrifice the faster focus.
and let's not forget, the 7D is a whole lot cheaper