Regarding the 50L, if you're seriously considering it, RENT IT FIRST.
The 50L is one of those where some people just fall in love with it (like RLPhoto), and other people get it and then end up hating it (like Studio1930 and myself). For me, it was missing focus very erratically, sometimes front-focusing, sometimes back-focusing, so MA didn't help. It also didn't have the same sharpness at f/1.2 that you get with the 85LII. Even at it's sharpest point, everything has a sort of haze over it. Stop down just a bit, and it's sharp as hell - but if I have to stop down, what's the point of paying the premium...
But again, that was just MY experience. Some people would save their 50L in a house fire before their wife... You never know which camp you'd fall into till you try it (rent the sucker)