The flatline barrel should allow you to shoot further as it puts backspin on the ball, I've heard however that the balls may well fly further but tend not to break on the target as the velocity as slowed down so much, I aint used one though so I don't know for sure. I must admit though I thought the flatline was more of a system then a barrel
As for barrel recomondations, do you use a lot of different paint? where do you buy your paint site/shop? 3 barrels are good of different bore sizes (small, med, large) as for make, Smartparts freaks are good you only have to buy the different size inserts!
Hope that helps,
Paul.