I borrowed the 1.2L from canon and the 1.4 from canon before I made my purchase... I love the build and durability and USM of the 1.2L, but when it came down to practice, to me, even after MA, even after a lot of playing with it, it isn't that reliable.... On my cameras, my AF struggled with it for whatever reason... some photos would be spot on focus, and others (even after focus confirmation on) the photos were off... It kinda gave me a weird "warmup" period where if i let the camera sit for a few moments and pick it up and start firing... the first 5-10 shots, the AF would be horrid... but once the camera and lens got warmed up the focus would target on and nail shot after shot after shot... This was on my 7D. I would be swayed in ruling a problem with MA if it wasn't for the fact that once it warmed up and had shots fired, it would eventually nail focus and be consistent from that point on... I also experienced problems with live view and manual focus showing focus and then taking the picture, the focus would be off... The lens just had too many quirks... the 1.4 is a lot older, archaic, clunky, sometimes hit and miss even with the halation, but it is a lot more consistent shot to shot and I frankly cant afford such a temperamental lens if I'm going to be plunking down that much money... I just feel canon whiffed on this lens even though i really did truely want to love this lens.