What sold me on MLU back when I was still using A-series Canons was an article I read in Modern Photography magazine back in about 1984 or so. They tested the New F-1 against a Canon with MLU, sorry I don't recall which one, shooting at a subject at 1/60 second. I don't recall any more specifics than that. But the images told the tale. The F-1's was noticeably degraded due to camera shake, whereas the Canon with MLU's was clear. Incidentally, about that same time -- might have even been the same issue, in fact, MP also published a brief article on the FTb. MLU was mentioned. Within a month, I owned one, and quickly became enamored of it.
What I can really appreciate about the New F-1 is the ability to customize it to one's specific liking, mostly by selecting the right focusing screen. Well, adding a motor drive or wnder gives you shutter priority, but that's a minor thing for me. Of course, when I bought my F-1N, I also bought the focusing screen I wanted -- a Partial Matte (I don't recall the designation for it). This also happens to be the configuration I use with my old F-1 -- a configuration I've used for many years. So I've set up my New F-1 to behave as close as is possible to my old one. Go figure.