I have a number of McGowan barrels. 20 Practical, 6X45 bolt action, 338 Edge. Absolutely no disappointment. The 20 Practical is a one hole gun. The 338 Edge, though built a hunting rifle, shoots right in with my F-Class 284 and took 3rd in a 2000 yard match. The 6X45 is a .5 MOA rifle even though it is the shortest and lightest build of the three.
If it's not a competition gun I go McGowan. And I guess I struggle to give real data as to why I wouldn't use them for a competition gun based solely on performance.