Burley, I've never run a 155 Scenar in any of my 308 MT's, including the current one.
Having said that, I can see no reason they'd not shoot very well. I've yet to see a MT 308 that didn't shoot several bullets sub moa, and its 1-12" twist should be about ideal for that bullet.
My friend Dober, who no longer posts here, uses the 155 Scenar quite a bit in his 308 Montana, and they shoot VERY well.
Load them with 46-47 Varget and rock-on.
The 308 MT is the absolute no-brainer Montana purchase if you want a no-fuss, out-of-the-box shooter.
I'm a 308 guy at heart, and I have a 308 Montana and am building an 308 M70 Extreme Weather... it's going in a McMillan Edge, PT&G Bottom Metal, Talley Lwts, etc., etc. It will be the "midweight" accompaniment to the lightweight Kimber.