Looking for backup, which one?

Looking for a back up camera for around $300. Looking at either a 20D or XTi, what are you opinions on which one is the better body and why?

I am leaning towards the 20D since its identical to my 30D for controls, but heard a lot about the dreaded Err99 issue.

Thanks

Depends on how much you use it. If it is just an emergency only camera, then maybe the Xti. Personally I couldn't go back to a Rebel series after using a 30D, so I would opt for the 20D. I've never heard about the err99 issue, but then again I don't follow the 20D news. I would suggest the 10D but don't think some of your lenses would work with it.

I believe the xti is smaller and lighter and has a couple extra mega pixels, but it shoots less frames per second and its controls/features aren't as easily accessible as the 20d's.
I have a 50d and my old xti as a back up, and believe me, there's a world of difference in usability between rebels and xxD models...so I guess it comes down to portability vs usability...