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kezeka -- Sounds like you are using the same focusing method as me -- center AF/One Shot. I'm having good results. Not 100%, but plenty of keepers to make its use a success. It is a finicky lens, no doubt, but not impossible to deal with.
I started with a used one of recent vintage on a 1Ds2 -- that worked great even without MA. I did need to play with MA on 5D2, 1D3, and 1Ds3 until getting satisfactory results.
If you can't get it working, see about sending the lens and a body (whichever is most important to you) to Canon for adjustment. I'd think it should be no charge if the lens is under warranty.
Oh, and I'm the opposite of you with the 85L -- I tried a CPS loaner and couldn't figure what all the fuss was about. At normal distances, it seemed a bit weak wide open. Closed down, it was good, but not worth hauling such a huge hunk of uber-expensive glass around. In fairness, 85mm, like 135mm, are not my favorite focal lengths. I ended up preferring the 90 TS-E, and especially the 100L Macro.
Obviously, there is no "right" answer, except getting the lens to operate properly and make you happy.
. . . or get a 5D3 (or 1DX!).