Perhaps this snow effect could be achieved by avoiding the use of SSS as it adds alot of noise and rendertime to your scene, ofcourse it depends on what type of snow you want but let's say generic snow for now while i'm speculating.
- For the often see glittering effect in newly fallen light snow (powder snow) you could probably make use of the glittering material normalmapped material posted recently on the forum and mxm site
http://mxmgallery.maxwellrender.com/new ... php?id=566
- Set the snow color value to almost white, give a slight blueish tone in a secondary layer which you fade in with layer blending into the main layer using a large and small procedural noisemap to give it some surface and density/variation.
- Make it atleast 3 layers, one main for the basecolor white one, one layer for the glittering, one for the big procedural noise, another layer for the smaller procedural noisemaps. This way you have more control over it and you can blend them easier.
This is just pure brainstorming now, i haven't yet got to test this if it works but i have a suspicion it would do the job of simulating the look and feel of snow.
/ Max