I've used fake stones for a sandstone texture I'm working on, using *very* small stones. It seems to work reasonably well, providing a textured surface while maintaining a smooth shape. The render I have running is just using a fake stones shader for a covering of fine "powder" on top of this clip file. If it works it may be quite useful for snow when you want a nice smooth surface that still looks like snow.
It doesn't seem to have too detrimental an effect on render times. Render times only seem to increse when individual stones start taking up a few extra pixels in the image.
I was also going to try this with Lucio's but I screwed up one of the nodes and have to go back to the beginning to find out what I did wrong. You posted this just in time for me to swap it over before catching the train