Other than his user name I see no indication that he is shooting at f/1.4. I am not aware of a medium format lens that fast anyway. The fastest I am aware of is the 1.9 manual focus for the 645.
If fast auto focus is very important for your work, then 35mm is the way to go. OTOH, if the problem is that the medium format autofocus is WRONG, but you don't necessarily need it to be that fast, just go manual focus medium format.