First of all, I only play woodsball, so this may not match up to your playing style. This is definitely a woodsball barrel, although I could see it working well for speedball as well. The first time i played with it, I cecked distance with my friends' A-5s and Spyders. All of their shots were hitting the ground after about 50 yards or so, while mine went at least 100 yards, maybe even 150.
While we were playing, the longer range payed off. There was one point where my friend's shots were hitting the ground around my feet, but I hit him without any problems. The other main benefit, at least when you're just playing with friends, is that everyone wants to be on your team.
The installation took about 30 seconds, but then I had to adjust the velocity. If the velocity is either too high or to low, the range is shortened dramatically. Turned all the way up, I could hold my hand a few inches out and down from the barrel and catch the paintball. It took about five minutes, but be patient and it's not that hard to dial in.
I will now address the most common complaints about this barrel. First of all, some people say that it is too heavy for prolonged use. If a little over half a pound is too much added weight, the 98 Custom was the wrong gun in the first place, weighing in at just under 3 pounds. Another complaint is that it makes the gun too long. In my opinion, long barrels are 14 inches. The flatline is 11, making it a mere 3 inches longer than the stock barrel. Also, the barrel supposedly decreases range, instead of extending it. As I mentioned above, you need to adjust the velocity to find the "sweet spot".
Buy it. It's completely worth the money. I give it a nine only because I believe that nothing is perfect.