Some of it has to do with what planes are supplied (sponsored).
The Extra is a really good design and if you look over the last few tapes there have been quite a few designs flown. One year there were about 7 Carden CAPS and Cristoph flew his own desinn CAP.
The Edge is really hot and some were flown however some pilots don't like them. Jason Shulman said "If you're flying an Edge you will need more than practice". There have been Wiggens / Katanas / Giles / Sukhois and others flown and there will be others flown in the future.

EXCAP232