I had a Windrunner. It is way up there on the cool factor because of being a takedown. They are accurate (MOA). The only bad thing about them is the brake. It's not real effective, so the recoil is heavier. I have owned 2 other 50's, and it kicked the hardest. I have never shot an M82A1, but from what I gather, they are hit or miss on accuracy, some guns more accurate than others. It is not going to be as accurate as a a bolt gun simply because the whole barrel moves during recoil. But I do not mean to say they are not accurate guns. They are way up there in the cool scale because of being semi-auto. The Barrett has a great brake. If I had a choice, I'd get a Barrett. The Windrunner is way over priced, and after having spoken with Bill Ritchie, the owner of EDM, on the phone, I think he's a prick. But hey, lot's of folks think I'm a prick.
My next 50 will be a Mcmillan, or Christiensen Arms Carbon Ranger.
BTW, if you get a Windrunner, Armalite sells a brake with threads that will fit the Windrunner. It is cheaper than the regular AR-50 brake, and is one of the best functioning brakes out there.