I get where people are coming from, when they say the SLO low end doesn't to tight, percussive stuff.
I think it gets plenty tight, if you keep the depth knob to 1 on the dial max, and hit it with a boost. Any higher with the depth knob and it adds a lot of low mids that flub up the feel. Gain knob lower helps keep it tight, too. I think the crunch channel is a bit tighter than the od channel, reacting much like a JCM800.
That said, I'd sooner grab my Ground Zero modded SS100 or Wizard Modern Classic, if I was looking for more modern, tighter, percussive chuggy stuff. Both have a tighter, more percussive attack. Neither have the hifi hugeness or singing solo quality of the SLO, tho the SS can be dialed in pretty close, to either amp. In fact, it's difficult to tell the SS apart from the Wiz when setup that way, listening to clips. You can feel the difference when playing.
Saying the SLO gets blown out of the water by newer amps, or is irrelevant... those are certainly opinions. I would say the former opinion is biased towards a specific preference. And the 2nd, is simply not true. For the "brutz", sure ok. But in general, The Soldano SLO-100 remains highly relevant as a cornerstone of modern high-gain amplification, cherished for its rich, dynamic, and articulate tone. It's highly regarded, often referred to as holy grail or legendary, for it's high-gain tones.
Here's a clip of the SLO I made the other night. 90s PRS CE24, TS 808, od channel, Marshall 4x12 with greenbacks. So, not the tightest setup. It can be more so with a different guitar, boost and speakers.
This one is a bit tighter/percussive:
Part of the same riff as the first clip, with an SD1 and SG:
Euge gets a pretty good sound out of his: