Just a bit of perspective, I too have a FM2, but do prefer shooting the F3, mostly because of the aperture priority which I use a good part of the time, the viewfinder, having been able to pick my favorite focusing screen, and I am better able to shoot while wearing glasses (I have the HP). But I do enjoy the FM2, and it recently spent some exclusive time out of storage for some landscape and baby photography, in this case the smaller size and weight was a factor as I was trying to economize as much as possible on those two factors. It was, of course, a pleasure to use. Awaiting return of the used artifacts, so cannot comment on my results, but do accept blame should they be less than the excellence that I know that camera can produce.
To say nothing of what can come out of the F6!
And I do have a spare F3HP body should you have any interest.
Larry