I have recently purchased four L lenses, and was very satisfied with the results I was getting, when I read all the complaints, I started to question myself and did some testing, not very scientific, but based on the type of work that I do and what I want from each lens all checked out honky dory and all performed as expected.
The flaws I started seeing and experiencing seemed to more operator error than camera or lens deficiency. We seem to forget that routine maintenance is still a key to good performance, (self and equipment), the one lock up I had with the 70-200 was cured with a good and thorough cleaning of the contact points.
Maybe I had horse shoes you know where?