What's a good second camera to have?

Now that I am starting to get some paid work I don't want to risk my beloved 5DIII breaking down on me (just incase) during a paid event. What's the best 2nd camera in your opinion which has decent ISO capability?

I was thinking T4i.. I can possibly put 35L on T4i and do full body portraits at 56mm..

and keep my 85L and 135L for my 5DIII to do half body / headshots / candids.

Looking at the T4i sample images it looks like the camera is good to go upto 3200 ISO printable and 6400 ISO for online use.

i haven't held the t4i, how do the ergonomics compare with the 5d3? i do remember when a local dealer let me take a 5d3 for a few hours, it felt a lot like my 7D - and I liked that.

7D just jot a fairly extensive Firmware update, as far as updates go... v2

http://www.dpreview.co​m …-firmware-v2-major-update