After reviewing Roger's autofocus tests at lensrentals.com, i decided to re-test my 50 f1.4 which has never been much good wide open even after a couple of trips to Canon service (minor improvement).
Unfortunately i found that both PD and CD AF are unreliable at large apertures. How can CD autofocus be unreliable even when i use magnification on a high contrast edge? i tested 2 new copies that don't have this problem (and none of the lenses Roger tested had a CD AF problem) and will probably keep one of them after investing an excessive amount of time.