Original 5D had a lighter AA filter and larger pixels than 5DII or 1DsII. The files had a different look. I really prefer the original "look" versus the new one....except the new 5DmkII generates way better colors. Their updated 14bit processing makes a visible difference in color capture and gradients.
It actually took me a couple months of shooting with the 5DmkII to warm up to is file rendering. There is detail for days, and you can really really work the RAW files well...but it had a different look. I'm used to it now. I have used the 1 series cameras and I still prefer the 5D cameras.
I have dropped my cameras, had them brown from dirt and dust, gotten them soaked in rain and waves, and never had an issue. (this includes the original 5D too) Just because they aren't "1 series" bodies doesn't mean they aren't field capable. No need to baby them.
Even after having used 1 Series cameras side by side with mine (inlcuding the 1Dv) I have never felt autofocus lacking. It has never let me down, and I have never felt that I needed "more" focus power. Center focus point and fast lenses make a difference however.