I've got one, once I got it properly tuned it was great. I had a bad regulator so back it went, issue solved, now the valve adjuster is moving with every shot, apparently it's a major disassembly job to get at it and put some thread lock/anti vibration on it. I'm debating if I'm going to do it or sent it back to Matthew, I'm leaning towards sending it back, it's new enough.
Update: I got thinking, and that alone is enough to send grown men scurrying for cover...The Valve screw is a screw, you adjust it from the stock end so.....why not unscrew it and see what breaks, well, surprise, it's a nice SS Allen machine bolt. pops right out, took some contact cleaner and cleaned off the oil, gave the threaded in the what ever it is a light cleaning, put a load of Purple Locktite on the bolts threads except for a little bit on the lede and let it dry a bit, then put it back in. A nice amount of resistance but not horrible, on quick testing it doesn't appear to be moving.