I have had both, and used vinyl and solid state. They were both excellent. They majored on tonality, for me meaning classical instruments sounding like real classical instruments rather than an impression of. I think a few people have said the s3/5r was boring, I think they didn't have powerful enough amps. It could sound a bit insipid below 50w a side. I used mostly Quad 303 & 405 @ 50 & 100watts. The S3/5r2 was a bit more all things to all men. It had the same tonality but with more bass and a bit more of everything to use a hackneyed phrase. I found with the s3/5r2 I was analysing music more. It made a harsh sounding record I have, Hergest Ridge sound very nice with a Quad 33 303. With other amps that record sounded more truthful and a bit rough. Strangely with this set up when I swapped to a Croft 25 pre I couldn't detect any difference with the Quad. My only impression, the speakers took what they had been fed and made it sound really good to me whatever the source.
As an end thought, of the two speakers I remember more fondly the s3/5r, supposedly the weaker one. I found that with classical I wasn't analysing so much, enjoying the tonality and the music and forgetting the deficiencies. Values of these are creeping up, especially with threads like these... however they fell off a cliff a while back when they were discontinued and the s3/5r2 was out. Maybe the rise is also a secondary effect of the ls3/5a madness that continues unabated!