I still reckon [think its been said before] the biggest market will determine board sizes{ie BOP in the states] as to what sizes the big companies will make and then event classes will be based on this rather than what the thoughts are of one elite racer.
In regards to the 12'6 surfboard class for beginners,
I'd rather see a 12'6 Novice Class on any type board,
and then a 12'6 Elite/Expert Class.
Firstly though you'd need enough competitors in both to have the two classes [don't think there's the numbers down here in Vicco yet but have to wait and see when summer finally gets here].
The 12'6 surf sup seems to be becoming more scarce with the new shorter wider sups on the market for beginners,
12'6 BOP/flatwater sup board now has more range and affordable,
when someone in the 12'6 novice class does well in a few events move them up to the elite class as they are probably getting more competitive anyway and would rather be in there to see how they go,
just my thoughts hope Scotty Mac doesn't drop in on me now at Mambo with a gut full of pizza

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Cheers.