When I purchased my 5D my 40D sat unused for a month and I decided I should sell it and invest in new glass. While I'm confident that was the best choice at the time, I'm now taking on some more regular paid gigs and feel like I'm playing with fire shooting with no backup body.
Most likely I'll start saving over the next several months until I end up with another 5D, 1D MkIIN, or maybe even a 7D, but for now I'm primarily looking at used xxD bodies. Not interested in Rebels. Also, while the 50Ds spec list is pretty awesome, I'm not used to live view, a good LCD screen, MFA, or any other modern bells and whistles, so they aren't really necessary to me.
With that said, in your opinion what is the best value for a backup body right now, the 20, 30, 40, or 50?



