Recently I did a photo shoot where I was using both of my digital cameras...the Canon Digital Rebel XT and the Canon 20D. A couple of times I fumbled with the settings on the XT as it is more finicky when handling exposure compensation and exposure lock (and different to the 20D).
I decided that it was smarter to have another body that was the same. My options were anything in the 20D-50D line. I scratched out the 20D/30D as I was not comfortable buying something used that was that old (although mine works fine). That left the 40D and 50D. The 50D was a little more $ than I wanted to spend, and after some research I felt that the additional benefits that the 50D offered over the 40D was not work the price, especially when comparing the price of a new 50D to a used 40D.
To my delight I found a Factory refurbished 40D - I thought great! Some peace of mind as it is factory refurbished, and a good price! After receiving it in the mail, a quick test showed it was defective...
I called the store and they had no other that I could exchange it with. I returned it.
After some searching, the only other 40Ds that I found were $100+ more than the first one, and at that price, I started looking at the 50D again.
In the end I got a 50D, and I am happy as I have the latest technology, a NEW camera, with warranty, and it matches my 20D perfectly. There are still debates on the quality of the high ISO performance, but I am satisfied with what I have seen so far.
The XT is already sold - with the money going to fund the 50D purchase - now I just have to sell a few more things....