As for OD vs Formula, just think about it if it is OD. Some kid buys this boat cheap and has to replace some worn out part. To buy this part new costs 100 dollars while he can go out and find one that works at the local hardware store for 15. Now he can't race, that isn't what we want. I have heard horror stories of people being turned away from Hobie events because of tiny little pieces that didn't match.