great to hear that. Thanks a lot for your sharing. With my 50L experience and reading people complain about 85L. I am really hesitate...
The 135L outclasses both the 50L and 85L with regards to AF issues. Not in IQ certainly, but with AF issues.
I'm not sure what you mean by "Not in IQ certainly." The 85mm is good, but the 135mm is better. Even when the 85mm is stopped down all the way to f/2.0, the 85mm is only barely sharper in its dead center (that's being compared to the 135mm when the 135mm is still wide open.)
The 50mm L is not even close. Its lack of sharpness has always been regarded as a big disappointment for such an expensive lens, and everyone has been awaiting a revision for quite some time in hopes that IQ will improve.
Here are some data that illustrate that the 135mm is as good or better than both of those lenses, even when it is put at a disadvantage of being shot wide open and the others are allowed the advantage of being stopped down more than one stop under their maximum aperture.
Additionally, CA and other aberrations are more controlled with the 135mm.
Units of resolution are resolvable line widths per picture height (LW/PH).
135mm L @ f/2.0 (wide open): Corners 2746, Center 3306
50mm 1.2 L @ f/2.0 (stopped down): Corners 1472, Center 3051
85mm 1.2L @ f/2.0 (stopped down): Corners 2425, Center 3472
For me, if anything, it is actually the focusing speed of the 135mm L that I wish would improve. Sometimes it's not quite there, when compared to the speed of the 85mm 1.8 or the 70-200 mm II.
I would be willing to pay $1,000 extra dollars to have a 135mm f/1.8 that had an extra 1/3rd stop of aperture plus truly modern focusing speed. That's not even thinking about IS, which is basically irrelevant to me since I use my 135mm lens 90% of the time to stop action, where IS is not a factor.