I just used one today and I really like the idea.
Its simple, easy to use and most of all its effective.
I put 500 rounds of chronic (from the indoor in Dec) through the barrel.
The concistency with a normal CP one peice barrel was +- 2, when I changed to the apex (with the dialer off) it went down slightly to around +- 3.
I couldnt notice the difference in accuracy though, both barrels were ball on ball.
So I tried the dialer thingy. It works suprisingly well.
The shots were still ball on ball, they all took the same curve in the air and landed in the same place.
The other settings give similar results. I would say the vertical settings are more effective than the left and right ones.
One thing to note is the barrel is EXTREMELY LOUD.
All in all I put 500 shots of pretty brittle paint through it, and even on maximum settings it didnt break paint.
Sticking it on ramping and seeing 20 paintballs per second draw a curve through the air is very cool.
People can slag this barrel off as some punter recball thing. But one thing is for certain, if you put this on a gun that can do 20bps it is potentially an awesome elimination tool.