I love my 20D but if / when it dies I'll be buying a new camera.
Personally I think that the older cameras are a bit too much of a risk and although I know that many people have bought a used DSLR with no problem I think I'd rather go for a new one and the piece of mind that a new shutter, clean viewfinder and new warranty bring.
That's just me though and the OP may have the same or a different view.
It is always slightly risky getting used.
I bought a 40D used, which I don't regret, but I wish I had gone through a site that offered a warranty (somewhere like mpbphotographic).
My 40D had a very minor button fault when it arrived. I dismissed it because it would have no effect on my shooting, but months later and the fault has got worse so now I'm going to have to get it repaired.
Seems likely the previous owner has knocked it right on the button and damaged it slightly.
I bought it from a well rated ebay seller, but his return period was only a week, so now I'm just going to have to pay for the repair. To be fair to him, the fault was so minor you had to use the camera for a while to notice it at all, so I highly doubt he sold it to me knowing of it's minor fault. Apart from that it is in excellent condition.
I don't regret my choice to buy used (no camera I could afford new gives the performance I want and get out of the 40D), just the fact I didn't do it through somewhere that offers a warranty, or I should have taken the very minor fault it arrived with more seriously.
I highly recommend the 40D though
But if you don't need speed or ruggedness, an xxxD body does do the job fine, and will take up less space and weight.