Threaded barrel arrived today, put it in the P30 and actually got a chance to try it out tonight. Was at a rifle range, so the closest distance I was able to shoot was 30 yards (also did 50), but I held about a 6" group at 30 so I think the barrel accuracy wise is good.
However, the thing flung the brass directly into my face, which I've never had this P30, or any HK, do to me before.
It was worse on the first 10 rounds, but did seem to get better the more I shot. I'm not sure if maybe it was my grip (I haven't shot the P30 for about 5 months now) or if it was something mechanically with the gun, but it was strange. Chances are it was me. I'll have to go to my range and bring both barrels, and see if it does it with the original barrel and if it continues with the threaded barrel.
Behold, the P30 "TB": (sorry for the potato pics, I promise the final suppressed picture will be with a real camera)