Nah, I would never switch. They don't even have a 85 1.2 so forget that. Plus, it's too much to switch to their system, in terms of financial constraints...and their lenses are uber $$'s anyway.
Problem for me, is the 5D outer points are horrible, so, I try to compensate with F/R and that doesn't cut it...so, what other choice do I have? A 1D anything isn't in the budget, so, there goes that option. I guess I'll just continue to make it happen, that's all...however I have to get it done. Might sell off some lenses, that's all. Not worth it to keep them, if they don't perform the way I want them to.
And the 5D2 isn't any help, most likely, in that dept. either...so, no need to upgrade there. 