Hi,
This is what I think. But 1st:
1) I am a Flysurfer Teamrider
2) I have tried all of the boards on your list
3) I use my own custom directionals, but if I had to use a production I would chose either the Flyrace or the Aguera.
Now to your questions:
1) The most popular boards in national comps are last years production models.
2) no idea
3) yes.
The Aguera and the Cabrinha are basically the same board. The fins that come with the Cab are OK but you would do good to replace them with better ones.
The Naish is great for Downwind, but is a bit unstable on the upwind legs. It takes a bit more skill to ride than the Aguera.
The North is probably the least performing out of all the boards on your list.
The Flyrace is damn easy to use and you will manage to easily finish top 10 if not better in most national races with it as it has almost the same performance upwind as the other boards on your list, and is easier to ride downwind as you can pull up the fin. Also you do not need to learn to tack and gybe. And it costs less.
4) Yes
5) Both, but if you really push them they will push back
. You will feel it in your legs after a few hours.
I hope this answers some questions.
--
Gunnar