Hi Tim
Welcome, the best way is to illustrate by example.
When I was flying my airwave sport on my 5 th hour of Ppg, I was struggling to penetrate into the wind. When a lovely chap on a reflex took off below me and had at least another 12 mph on me.
Simple, I bought a reflex wing, for it's speed advantage.
People will wax lyrical for hours on reflex stability, and rightly so. But for the average pilot, flying in the uk in benign conditions, speed is a very real advantage.
From my own experiences and chatting to people, reflex wings are now so good that they perform like a standard paraglider in slow trim, and a speed machine, with the trims out.
Be aware that not all manufacturers are the same, in my opinion no one embraced reflex like paramania or Dudek. I currently fly a synth and will be changing for the highly acclaimed fusion shortly.
Best of luck simon