I've used it in moderate snowfall – nothing more than a few inches. It's got a fair amount of moderate angle surface area, so you'd likely want to knock the snow off in a serious dump and make sure to keep ample tension on the ridgeline. For 90% of winter use it's likely good.
One consideration is pitching the shelter. With the SS2, you've got a fair amount of essential stakeout points (ie. the shelter would collapse if the stake pulled out). There's a minimum of 6, but you really want to go with 8 stakes for any sort of decent weather, and for significant snowfalls you'd want to be using all 10 (10 stakes total with 6 of those being essential). In winter conditions staking can be a bit of a pain, so I prefer something a bit simpler (ie. a 4 corner mid + 2 extra stakes on the long sides).
Some of the nice things with the SS2 is that you can replace the inner with a groundsheet and then make it a hot tent (ie. TiGoat wood stove), which works nice even with 2 occupants. It's a great tent for mild-moderate winter use, but there's other tents I'd select for camping on a windy ridge with heavy snow in the forecast.
