Got mine. In fact, its the one in the"kit" section of the Costa Ludus website (that exact one, same serial no as it happens) The photography was done over here in the UK and I was lucky enough to receive one from the owner of Lantac who is a friend.
Chris Costa did some evaluation of the break and apparently really liked it - he's going to be selling the Dragon with the Costa Logo on it, with Rainier Arms and Brownells listing it. I know there is another production run being done at the moment and they are due to be back on stock soon, for those interested.
Our AR15's are straight pulls so we don't necessarily feel the benefit of recoil management for semi-autos that you guys seem to be getting according to the reviews.
That said we don't have the effect of the bolt carrier cycling back either so what we do feel is the effect of reducing the recoil on a single shot as if it were a bolt action.
Must say I am impressed and found the gun moved less and remained on target - the recoil was reduced by quite a bit as well. I will caveat that by saying that I haven't shot with every muzzle brake on the market so I can't say for certain where it ranks, but I do know that it is the best muzzle brake I have used so far. Also, my opinion is probably of limited use to you guys with your semi-autos.
I'd check out the reviews from your side of the pond for more info though. There's quite a few people with semi-autos who have the brake now and they should be able to provide you with a better evaluation for use with semi-auto than I can.