There's the Signal Omni 150. I think the NS SL comes in 151...
For an all mountain deck you should be able to comfortably go up to 150 or 151, especially if its rocker as they're easier to manuever.
More to come when I have more time.
Libs aren't light, so if its bigger than you were looking for it will really feel too big. Berzerker was my second thought, but yeah 55 might be a bit much.
It's been a few years since I've been on a TRS, but it has been in the past the only thing from the whole of Mervin I didnt hate, aside from magne which I'll always hate.