As long as you are a back player, they are great. I've heard some complain about them when they get stuck on a small speedball field. As long as the barrel is assembled straight up and down, and you hold the marker straight up and down, they will shoot farther than anything out there. If you tilt the marker to the side, you can get some wicked "curveballs" going. Of course, sometimes that is an advantage
. There's nothing like shooting around bunkers to ruin an opponents day.
Another thing to keep in mind about the Flatline is that you don't simply unscrew it and squeegee it like you do other barrels. You'll have to run a squeegee throught the feed port on the side after unlatching the feed elbow. It's nothing major, but some people forget that fact. Also, not all squeegees will fit through the feed port.
Some people have reported that it can be picky about what paintballs shoot well through it. If you are stuck with a certain brand of field paint, you may want to check with Flatline owners and ask their opinion on how that paint shoots through the barrel.