I bought a 92/93 Rockhopper frameset and just built it up yesterday. I built it up with a Hollowtech II Deore single-ring crankset, a mid-90's Shimano rear derailleur, wheels and 7-speed 11-28 cassette from a 1995 Trek 820, 55mm Big Apple tires, a new Acera front V-brake I had sitting around and odds and ends for the rest of it. The only original components are most of the headset and the seatpost clamp.
I think this is the nicest riding bike I've ever owned. I've got other bikes with similar geometry so I think the difference may be stiffness. The Rockhopper is the one bike that appears to have larger main triangle tubes, especially the top-tube. Also, the chainstays look massive compared to my other bikes, even other 90's MTB's. I'm a 400 lb rider so I put a lot of stress on a frame and I'm thinking maybe the Rockhopper is just a little more stiff than the others, so it feels better to me.
The only issue I have is that it's too small. I have a huge amount of seatpost showing and a high quill adapter, a 25 degree stem and hi-rise handlebars. Looks goofy but a larger size (which I've been watching for) would likely be too long in the top-tube for me. This one is stretching out more than I like. I keep thinking that a 26" Long Haul Trucker is the answer to my prayers but it just doesn't look that stout where it counts (particularly around the bottom bracket). I think my only recourse is to go custom, which I already want to do, but it will really stretch out the wait. I'll probably go with a custom R&E UTB or a custom Co-Motion Pangea. Jan Heine bringing out 26" x 55 mm high performance tires really sealed the deal for me.
This is an older image from where I threw some parts on it shortly after buying it:
Here's a small size R&E UTB. Note the large chainstays behind the bottom bracket and the ovalized and way oversized downtube!