Realistically (like, I'm speaking honestly right now)
Carnage Scissors is only useful against zoners, and only if you have another 50 heat to rapid, since that's 6k right there. You really really really are better off saving your meter for RCs or CAs. It's a great super when going for the kill or attempting to gain a health lead (or even gain some health back).
Also I only use BK when I feel like being an asshole, it's really, really, REALLY, not necessary.
So yeah, it's a pretty crappy super.
But hey, we have Inferno Divider, that's why we don't have a great super, you know? We don't need it.
But man, the satisfaction you get from using CS as a reversal can't be replicated.