Congrats on the lens. Small world I guess.
Perry, you make it sound like Matt and I were the strongest advocates against the 50L, but I don't think that is true. I think it's pretty clear we give the 50L it's due. (Along with deserving negative remarks about it.)
My 50L is starting to grow on me too, especially once I got over the focus testing phase, which I was forced into because on my older copy I was seeing some major problems in real world shooting. I am really happy that it went to Canon and not another person b/c it really did shift that badly. So the positive was that they eventually exchanged my old for a UW date coded one. I didn't notice an issue at all in real world shooting, it was just a pleasurable experience.
I suspect on the full bodied shots, you would be far enough from the subject to be outside of the danger zone. At f2.8 you would also have enough DOF to avoid most of it as well. I can definitley make my copy shift all day long when shooting between MFD and 4 feet so. No need for charts for that. So I just try to stay away from that type of shooting. Sometimes I can't though, and it can be frustrating. It is also rather soft and has that ghostly look to things wide open at those distances. My 35L kicks the living day lights out of the 50L at those distances and at f1.4. No contest.
It's definitely a great lens if you can work around these issues. I use mine as a walkaround lens often, and it does very well in that capacity.
Yeah Nick, I can force it to shift if I try as well, it's incredibly easy to do, but I find it manageable, especially because I have the Ee-S screen and I can adjust accordingly. Although on mine it behaves more like simple backfocusing at close distances (since when I press DOF preview there's very little shift) - so it's super easy to manage and doesn't have an impact on my shots - I looked at all my shots from today and they were either bang on or so far off that it had to have been my fault (i.e. well outside shift range).
You were 100% right about the outer points though - the accuracy is hugely improved, even flawless - and I think I read that this is because shift occurs toward the centre of the image circle.
I agree with you about sharpness - it's pretty sharp, but sharpness is not its best quality - its strength lies in many of its other qualities - colour, bokeh, contrast, INSANE resistance to flare, handling etc....
It's a little softer than my 35L was at equivalent apertures (though not too much), and nowhere near my 85L, but it's definitely usable and an improvement over the Sigma in every way.
I really, really like this lens 
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How sharp is it wide open? I've heard mixed reviews, and most say it gets pretty good at 1.4.
^ See above
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