Well I finally got this out to the range this weekend. I had to re-sight in the scope of course but once zeroed it worked great. I was able to keep my face a bit back from the charging handle and also had enough stock to get a pretty decent weld. 2" group at 100 yards from the bench, and I could do better with some effort. The real difference came when shooting in the stances, since I was able to get the stock extended enough to not have to scrunch my shoulders and neck down to the carbine.
It seems to hold zero pretty well, too, if you screw it down to the same tightness each time.