With regard to Rotosounds (RS66 is my favorite 4-string set)... Rotosound Swing Bass was the very first stainless steel roundwound. Stainless is harder than nickel plated high-carbon steel and much harder than pure nickel winding wraps. That hardness is what gave them the super-bright tone when they were first introduced back in the late 60's. They retained that sound a little longer since fretting wouldn't deform the harder windings, too. The windings were less prone to corrosion from handling which helped keep the bright tone too.
The problem is that the additional string hardness could cause more wear on the softer nickel-silver (which is really mostly nickel and no silver) fretwire.
One of the popular combinations in the early 70's was Rotosounds on Rickenbacker 4001s which would be somewhat disasterous. The Rick had very small frets to start with and they normally came from the factory with flatwounds, so it would be hard to find a worse combination. I was the original owner of a 1973 Rick 4001, I used Rotosounds and did find that playing seemed to cut more grooves into the tops of frets than any other bass I've ever played them on, so perhaps their fret wire was a little softer too. I used them on a really bad Fender P-bass around that time too and didn't really see any signficant wear (of course, the action was so poor on that bass I probably wasn't strong enough to fully fret the strings!).
These days, I doubt that Rotosound is any better or worse than any other stainless roundwound. I prefer the less bright sound of nickel-plated wraps myself, but I doubt that there would be much difference in wear there. Pure nickel wraps would defintely have less fretware, and these days they've become common again for guitar (and are awesome!), but pretty rare for bass (Fender seems to have a set which I've never tried).
The funny thing about Rotosounds are that the classic RS66 are stainless steel but to me behave more like a nickel-plated steel string. When you first put them on, they have an amazingly open, grand-piano tone. That bright edge goes away for me after just a day or two even if you only play a little. The less bright sound that it degrades to stays that way for quite a while. Other stainless strings I've played - Markley Blue Steels and DRs seem to be bright when you put them on and basically never change their tone. I think this is why most basses come with stainless steel strings as original equipment - they will maintain most of their sound for the life of the time on the dealer's wall. The behavior of the Rotos is much more like nickel-plated rounds like GHS Boomers.
