I say they are good to go, great if your on a budget
I purchased a 10.5 upper with their in house slick tube rail. I have had the upper for about 6 months now and have put a little over 500 round through it, I have changed out the rail and the muzzle device and have had no issues.
If you do some research they had an issue with their melonite process, basically they were installing the barrel extensions, then meloniting them. So when people went to take off the muzzle device the barrel would come loose form the extension.
Radical said that it was some employee that was cutting corners and the issue is fixed, like I said no problems with removing and installing a muzzle device on mine. (did it last month)
Was impressed with the quality of their in house rails was expecting ebay china quality, if it wasn't so wide I would have kept it on the upper.
hope this helps.