Are they worth the money. do they perform better?

I don't fly them, but know several people that do, along with the guy who sells them. Apparently the biggest benefit is that they keep the thrust vector more defined, which can make a big difference when you're doing 3D/high alpha maneuvers. The focused column of air makes the tail surfaces more effective. The prop also has a fairly wide blade, which helps generate more thrust at lower RPM's. At least that's what I've been told. Cool factor is there, no doubt. One thing I'd worry about is catching a tip on the ground. The tips are carbon fiber, but they're under tremendous force, and it doesn't take too much contact to rip them off. If not too bad they can be sent back to be repaired.