I love the Semislicks. They need a bit of a change in riding technique. Lean the bike just a tiny bit and they bite really, really good. Actually better than most xc/am full knob tires. The side knobs are really beefy on all three big brands.
I liked them in the 26inch variety (Rock Razor Pacestar, Snakeskin) even enjoyed them in the wet. It´s a bit slipperier, but it´s fun.
I LOVE them even more in the 27.5 variety, as they are a hair grippier and still as fast.
Right now I ride the Minion Semislick (the one you´re mentioning) and while it doesn´t roll as fast as the Rock Razor in the hard compound, it offers quite a bit more grip and has a nicer rebound. Not as pogo-like.
I am actually amazed how much grip it (Minion SS) offers when braking or climbing.
The Specialized Slaughter I rode for a couple of weeks was a 29er Control. Fast rolling, really a lot of grip - it´s a 29er after all. But the sidewalls are a joke. The DH-variants of the Slaughter are really heavy 1kg tires.
I feel that the Minion SS EXO is the best compromise for enduro riding. It offers more protection than the Snakeskin Rock Razor and the Slaughter Control, yet still has an acceptable balance of weight and rolling resistance.
Also it offers the most traction of the three tires. Rolls at least as good as the Slaughter, a good bit worse than the Pacestar Schwalbe though. The Rock Razor is ridiculously fast on pavement. But it does ride a bit xc-ish when pushed really hard.
One thing to beware:
The Semislick tires are a nightmare for all rims when they´re run tubeless. I didn´t have a flat, but my rims have dents, dents, dents. The missing rubber knobs right over the shoulders of the rim really make a difference. Don´t go too low on pressure.
Might be really good with your ultrawide rims. Or you´ll destroy them. Don´t know, never owned wide rims, yet. :D
I have to say: I think braking traction on the rear wheel isn´t really important as long as you have proper sideknobs. I actually feel the new style semislick tires improve my riding.
My braking technique is getting better and more controlled, more front brake and not in corners. But different strokes for different folks for shure. If you prefer full knobby, that´s fine. So many good tires out there.