S/Lab is Salomon's race line, and the Ultra V2 is the long end of it — the shoe built with François d'Haene for races that run into double-digit hours. It sits low, it holds its shape, and a profeelPLATE between your foot and the ground takes the edge off rock without cutting you off from it.
It suits you if you race ultras and want to feel what you are running on. The 8 mm drop and the firm platform reward a runner who is still landing well late in a race.
It is not a trainer. At 290 g it is not especially light either, and the price only makes sense if you are actually racing. For everyday trail miles Salomon has softer, cheaper shoes.