I have got one on now and another on the way. Getting about 50-75 fps over previous barrel. That seems to be the norm with everyone using them.
It is faster, easier to clean and have never heard of problem with bullets coming apart and I have seen a lot of them shot over the last 3 yrs.
Lot of records and matches been won with them. In last two years in particular way more than their fair share. Right now, by all accounts he is building the most consistent and one of the most accurate (if not the most) barrels made.
His attention to detail is what sets him apart.
He is also running a slight taper (.0001) towards the muzzle and this seems to lead to better accuracty. See the Feg Precision shooting and Mar for an article by Calfee on this very thing.
BH