The only ones I've heard about have been normals to normals. There might be some hets floating around... but no one's saying. It takes some work to get these two to produce offspring, and there aren't many people willing to take their lesser out of the BP breeding cycle to try and create lesser superballs (A great many people don't agree with creating hybrids at all).
I agree it would be cool, though. Maybe a pastel superball? And who knows... maybe someday there will be a killer superball, lol.