The 5D will have shallower DOF. I can't remember how much. Just over 1 stop, I think.
That is correct, I believe, unless BJL is wrong ) . I have to confess I've never actually tested this because the situation is complicated by the different performance of different lenses at different f/stops, as well as the different resolving capabilities of different format sensors.
I understand that theoretically, if one had a 12mp camera like the 20D with pixel quality equal to the 5D's, and
if one had a 50mm lens which at f5 performed as well as the 80/1.8 (for example) at f8, then the DoF multiplier would be 1.6.
But these theoretical ideals rarely exist, so it's all approximation.
Sorry! It's not the 80/1.8 but the 85/1.8, so there's another complication.