I'm saving up for the SLO 30, since that hopefully works at a more reasonable volume. My experience with them is extremely limited, but I did get to try an HR 50+ an odd decade ago and it was hands down the best amp I have ever played through.
The HR50+ was the best amp I every owned and could be had pretty reasonable back in the day, I traded a Boogie MkV for it, lost a lot of bells and whistles, but got the tone I wanted.
But sorry, can't speak to the new SLO vs the old SLO.
When I think of the SLO I instantly think of DiMartini, and even Lynch as he would mix a Marshall and a Soldano together in his sound (like on BFTA). But Warren didn't start using them until Detonator. Everything else is a boosted Plexi according to him. Same Plexi that Lynch tried to take from him actually.
BFTA was primarily the purple Marshall. According to George's old website, the SLO only came with Wicked Sensation (there was supposedly an ENGL at work too, but I can't hear it). I guess we have no guarantee for the information being reliable, but it would help explain why WS sounds so much smoother.
https://web.archive.org/web/2004041...elynch.com/rigs/studiorigs/backforstudio.html
https://web.archive.org/web/2004041...gelynch.com/rigs/studiorigs/wickedstudio.html
Lynch uses anything with tubes.
You never know what or when.