I loved my 40D (RIP). I only replaced it with the 7D because someone stole it. 10.1 MP is more than plenty to get incredible, detailed photos. I also have the 5D2 and I can't say that I would choose the 5D2 over the 40D (or even better the 7D) with regards to wildlife shooting. At 6.5fps, the 40D is a workhorse. I look back at the photos I got from my 40D and I couldn't be happier. It's a solid camera (as good as the 50D, in terms of image quality and performance) and I would still be using it if someone else hadn't decided that they wanted it more than me.

I have a friend who bought the 5D3, (she is one of Southern Arizona's premier wildlife photographiers) and she is not 100% convinced that the 5D3 is all that with a bag of chips. She says it's a wonderful camera, but there are things that she would still use her 5D2 over the 5D3 and she loves the speed and quality of the 7D/40D.
There is NO 100% perfect camera, sorry guys. I find myself grabbing my 7D over my 5D2 when I go shooting wildlife. It's fast and responsive, like my old 40D was.
I would say a solid 7D is worth ever penny over the 5D3/1DIV for wildlife shooting, esp for the extra money saved on the other 2 cameras.
Both samples taken from the 7D. Don't let the quality of the "size down" (I had to really size them down to post them) discorage you. The full sized photos are amazing! (The weaver taking the bath was taken at ISO 800. {No noise reduction} I have no issues with the image "noise" at higher ISO's from the 7D. The photos are simply amazing!)
Oh, one more thing, the 5D2 is rated for 1/4000th of a second max shutter speed and the 5D3 is rated at 1/8000th of a second max shutter speed. The 7D is also 1/8000th of a second shutter speed like the 5D3 and 2fps faster for over a grand less! (depending on the sale/where you buy it from!)

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