Well, I finally took the plunge. I've just recently purchased a lightly used Canon 7D.
Lots can be found on the internet about the 7D's specs, particularly in regard to bird photography. A while back I had decided on a Canon DSLR system, but it took me a while to decide which body to purchase. I narrowed things down to a used 40D, a new 60D, or a used 7D.
I had ruled out a used 50D because reviews from birders seem to find little upgrade from 40D, and they are going for $200+ more than used 40Ds. I also ruled out a new 7D because, with the camera already being over 18 months old, it will be due for a successor sometime in the next 18 months. I thought the 'lightly used' option would be the way to go if I wanted to upgrade to the eventual successor, because I won't end up losing as much in depreciation over a short period of time.
The more I read about the 7D and spoke to other birders about it, the more I wanted it. Its reportedly very good high ISO performance and great autofocus system were major draws, not to mention the HD video capability (available in the 60D but not the much older 40D).
So then it became a matter of trying to find a good deal on a lightly used 7D body. If that couldn't happen, I was going to pick up a used 40D (an incredibly popular body among birders).
I shopped around for a few weeks, monitoring various places for used 7Ds and getting a feel for what they were going for. I picked up a 7D in great condition for a decent price. Just the body, no lenses or extras.
Now the question is...which lens? I've narrowed it down to two popular choices: the 100-400mm IS zoom and the 400mm f/5.6 prime lens. Both lenses have their pros and cons and both of them deliver fine results, as evidenced by the many folks who post their photos online.
I have just rented the 100-400mm zoom for the week, and actually took it to Maine for the weekend. Sometime next week I hope to borrow the 400 prime from a friend for a few sessions as a comparison. I will share my impressions of both lenses later. Bottom line is that I'm going to go with whichever one feels better and makes me enjoy photography more. I have no idea which that will be, but I'm looking forward to finding out.
Now I just have to figure out how to use this damn thing...