I've had a few in my time, still have 2 now, my Team which is my keeper and another us built frame which I've had converted to disc and to run a bearing rather than bush at the chain stay pivot point. One day I will get built up. Both have alloy rear ends.
Rear end wise I don't think there's a lot of difference in terms of ride. The steel end without the pivot is heavier, I think some had removable mech hanger, some didn't. Early RTS had steel rear, my 93 RTS 2 had one too
The alloy ones are lighter, while I love an RTS, they can be said to fail/ crack at the rear bushing point, chain stay area. I'd say this happens when not maintained, never had this happen on any frame I've owned, though my RTS 2 did crack at the BB pivot weld.
If you are looking for a frame, check for cracks in these areas and also the headset. Make sure the shock is in working order too as they are fairly proprietary and I've only found risse as replacement options which are expensive. I believe noleen still sell and service them, but both options are stateside so expensive and likely to be more so when you factor in taxes for import. I have seen an rst unit, but it's pretty basic and heavy iirc and if you can find one.
Rocker bearing are another thing to check, though can be replaced easily.
Some frames had bushings in the main pivot. Top hat shape and hard to come by. Others had a pair of bearings with a centre that pivots/moves, can't recall the name of this type. They had a small spacer between them. I assume you can replace the top hat bushings with these.
I have most of the bearings and bushings as Soares for my 2 frames, plus some spare rear ends so if you need anything measured I'm happy to help as I am a big RTS fan and like to see them restored and used so happy to help with anything if I can.