How is the video with that setup?
I actually haven't had the chance to test the video with the L series lens setup, but I'm going to offer that it is very similar or the same as shooting with the T4i since the two cameras share the same sensors and processors. I believe they also share the same contrast method for Live View autofocusing, but I personally try to avoid using autofocus (too much) when shooting video! (Too much racking that doesn't look intentional/"cool"!) So, if you're not using autofocus, I'm going to say that video would be the same at the T4i, i.e., very good. The EOS M also has a mic in jack, so there's that...
Dan at H and B Digital