Was it always a back focus? I.E. something that could possibly be adjusted on camera, or with their USB attachment? I'm okay with spending countless hours adjusting stuff to get it to work, if the focus is consistently off in the same direction. I'm not doing live events, sports, wildlife, or anything like that, so I might be okay with using manual focus all the time, but it's very, very annoying. Especially since I have a degenerative eye disease and I'm always second guessing whether my manual focus is correct on the tiny live view screen.
Seems like my only option with Canon, and not spending like 6k, is to get a few primes (already own the 40mm pancake), and pull out my kit lenses if I desperately need zoom in a video shot where digital zooming just won't work. Not opposed to looking at other systems if I can get good lowlight, good video autofocus, and a good zoom lens without having to save up for a year.
What did you end up replacing the sigma lenses with?