So far, and I'm only 48 so take this with a grain of salt, I've found OP more than sufficient to hold mobs in everything I've done. I'll usually toss one down between full rotations which is sufficient so far to allow me to not to have rotate through mobs yet. I'm sure this will change as things go on but I pretty much always save a full Wrath stack for IB. And I don't even have Flash as one of my additionals. Again though, I'm sure that will change as I go on and the fights get bigger with multiple mobs that need to grabbed/held.