I'm going to say, despite the fact it's one of my favorite Pokemon, is no. Darkrai belongs in an uber environment and pretty much is there to stay. It tears a hole in most teams, even with the simplest set of Dark Void/Nasty Plot/2 attacks. Unless you are packing some type of blatant counter, like a Scarf Fighting Type, a Lum Berry super-attacker, or in DW's case, Techniloom, it's going to take out multiple Pokemon. I used the Pokemon a lot in Gen 4 ubers, and I ended up like 100-2 in both Singles and Doubles. People at league and other places I went to personally requested I do not use it or they would not play me.
So, my answer is, until they change some things, absolutely not. It never has had a place in OU of any type and takes very specific things to take down in order to stop it.
If you tested it, it'd get the quick hook so fast it isn't funny, unless everyone on the ladder happened to run Scarf Terrakion and Heracross to no end.