When I was deciding on which barrel to order from Pac-Nor, I did a search (that was about a year ago) and the general opinion was that the 3 grooves were supposed to be a little faster like gohip said. Also supposed to last a little longer. I couldn't find any negatives at that time so thought I would try one out.
Hearing a lot of good about 5R barrels now but those weren't being talked about back then.
