Who's using Shutdown?

I've seen a few posts on this, but nothing concrete. Just curious, for those who have/are using shutdown on corners and safeties. I understand the consensus is UC is the best ability and that's what I've been using, but I find myself running more man coverage with occasional zone adjustments based on what my opponent is giving me. I've heard some say that Shutdown is better than OSA and I figured running reinforcement + shutdown would be a nice combo for man and man knockouts. Then, I could effectively add the zone knockouts I use in the other slots. Thoughts?