I used to own an SF7 many moons ago (about 10 years or so).

Personal opinions - very nice camera! Not the latest and greatest feature-wise but a solid camera and as you say, it felt good in my hands. I used it as a second body when I was still using Pentax kit.

I'm busy scanning my 35mm negs at the moment so I should be able to show you my results with it soon.

Don't worry too much about dust on the mirror. It can be cleaned out easily enough. Same with the prism. Just be careful not to damage the mechanism. What you need to be careful of with SLR's is damage to the shutter. That can be expensive and hard to repair.

I know that digital is the rage now but I still have a very soft spot for 35mm SLR's. I suppose that's because I used them for many years before going digital.