I just got back from Ohio Dreams, which uses MSnow (the white version, not the orange) on its water ramps.
First of all, Ohio Dreams is absolutely the sickest. If you're in the East and don't want to shell it out for Windells, then OD is the place to be.
As far as the MSnow works, it's actually pretty sick, for the most part. It definitely gives you some speed, but it has it's flaws as well. First of all, it was advertised to last 20 years. While I was at camp, they had a problem with the bristles on 3 year old MSnow snapping. It looked like that might have just been a bad batch though, as the problem was localized to a few spots on the ramp. Furthermore, the little spikes themselves feel like plastic knives. DO NOT FALL ON MSNOW. I repeat: DO NOT FALL ON MSNOW. That shit will tear the skin off of your arms quicker than you can ask if the camera was on. Seriously. Finally, it doesn't work that well with snowboarders. It's really hit-or-miss as the whether or not a boarder can have success on it. Some boarders just can't stay up on it (and thus get their exposed skin turned into steaks).
On the whole though, it definitely did its job for getting us off the ramps and I'm a fan.