Final update - the Supersprox pictured on the Rocky Mountain ATV web site is nothing like the sprocket you'll receive. For myself going forward, I will have to default to the standard Renthal countershaft sprockets (as the Ultralite version has been discontinued) - nobody else manufactures anything near the level of Renthal quality. I imagine within the next year or two, even the standard Renthal sprocket may disappear as it only fits a few older, less popular bikes...
If anyone finds anything else worth purchasing, please do share...