I throw a lot of discs and try most new stuff that comes out. I had at least 5 Grooves and one point, and I can attest to their suckiness and inconsistency. They had two main problems...They didn't really fly as advertised and they were very inconsistent disc to disc. I just don't think that wing design works in a disc that fast...I found most Grooves to resist flipping from a hyzer release, but once they got over they became increasingly unstable. So basically it was tougher to get a smooth S turn than with any other high speed disc. The transition from hyzer to flat to anhyzer was never smooth.
My views were reinforced this spring when I played pre-tourney doubles at a ball golf turned disc golf course. My partner was a guy who was there volunteering, so he had not brought his golf bag. Someone had given him a couple discs to use, and the only driver he had was a Groove. This guy is a young gun with a little more power than I have and pretty good form all the way around. Over the 18 holes he tried to work that disc every which way, and no matter how he threw it he just could not get a pretty flight. It either flipped abruptly high up in the air and came diving down, or never got flipped and stalled out. If he applied any power on a low line it was extremely flippy. By the end of the round he was like "thank god I never have to throw that disc again!"
Now that the Nuke, Katana, and Halo are out there is no reason for anyone to buy a Groove. I expect OOP status at some point in the relatively near future.