The FM2n is a glorious piece. Closest I come in Nikon bodies is my old F2S, though I do have a FE. I've never actually handled a N80. I also have a F4S which really is an amazing camera. Big, heavy and yet incredibly delicate and precise to work with and still all of those lovely dials like a "real" camera.
Oh yeah, I also have a N2000, gift from a neighbour when they moved last Fall. It came with the "good" 50 f1.8 AIS so a nice little present.
What I like about using old glass on the full-frame Nikon bodies is that apart from having to dial up the lens I've mounted from a list I've set up in the menu (hooked into a single-button operation) I just use them exactly the same way as on the film bodies. I even get "Matrix", spot etc. metering with most of them. The only company to make the whole thing so seamless was Nikon with Pentax runner-up.