lol You must be a healer, concealment is only fine against lesser geared opponents/clothes. ... Stop playing into Bw scoundrals are fine. No one want them in rated WZ or Ops ;There is a problem.
Having played a Concealment Operative to 50, primarily PvPing, I can assure you that this is not the case. Like any class, the concealment op has a problem fighting better geared opponents. But I have never had a problem where I continually lose against equivalently geared opponents.
The main drawback to the concealment op is that the "ambush from stealth" attack doesn't come until level 36. So prior to that level it's really a matter of just hiding and waiting for your opportunity to strike. But from 36 to 49, if you know what you're doing, you can single handedly swing a warzone's outcome. Once you hit 50, then it's back to the waiting game until you get geared up.