Never heard of a grazing wheel. I think I'll stick to the nori I can pick up at Walmart for a couple bucks, though I hate how messy the tangs are with it.
The New Era grazer rings are good. I use them once a week in place of the daily nori. DiY'd a magnetic holder for mine as the supplied suction cup is a pain. Only downside is it kills the foam production on my skimmer for a few hours.