I’ve been really really surprised by the speed of rocket rons. not a semi slick, but I’d swapped out what I’d considered a fairly rapid tyre, the spesh S works fast trak for a ron and it feels both much faster, and much grippier on looser stuff.
fastest tyre I’ve used on a MTB was the terrano XC. it’s very very quick, and does hook up albeit using the small hexagonal channels rather than traditional tread and leaning heavily on softer compound, so great for hardpack and rocks. falls over on anything damp, but still corners OK once it slides over to the edges.
I did find it crap once it started to wear though. Once you lose those channels, the tyre has nothing to offer.
as an aside, I’d never use a ss on the front, I was scarred by my experience of using a wildgripper sprint s back in the day..