I dropped and broke my 50mm MK11 1.8 which I had been fairly happy with exept the AF ability in low light. For a while now I had pondered on whether or not to get the The 50mm f1.4 / f1.2 or maybe something wider. I had tried the 50mm f1.4 on a 30D and did not make a purchase. Then a while later having the 5D MK11 with me I tried this lens again and made the purchase. I am very happy with the results so far. Great IQ with fill in flash at f1.4 with an equally satisfying rendition of colour.
needless to say the the IQ gets very sharp as the aperture is stepped down with f8 / f13 being as sharp as my macro 100mm f2.8.
This lens is a step up from the plastic f1.8 in so many ways and well worth the higher price.