Upload & Sell: On
First you said
I disagree about the 50L. It is fine with 5DII AF (center point).
Scores of threads here over the years testify to the problems that many have with 50L; there have been a couple in the last week. Some lens/camera combinations have issues; some don't. That is a fact.
Then you said
Sorry, the sigma 50 is iffy with autofocus. Get the lens you want.
As if the Sigma 50/1.4 somehow is unique in that regard.
Both lenses are "iffy" with the autofocus of many cameras.
Both lenses are fine with the autofocus of many cameras.
Both are, in fact, something of a gamble, either because of sample variation or some other issues. But to pretend that one is "fine" while the other is "iffy" simply ignores the vast weight of evidence to the contrary. When the 50L and the camera body make beautiful music together, it's undoubtedly an excellent tool, and can do (in the right hands) some things the Sigma 50/1.4 cannot do. But whether those things are worth an extra $800 to a particular purchaser, and the gamble that the lens often may not focus well, is a legitimate issue.