But for what reason is this critical data being withheld?
I don't think it is being withheld. It's more likely that none of the people on this forum actually wrote down all the figures, and they're reluctant to post inaccurate data.
As has already been said, the only boat that was right down to weight was Hans', which is VWM hulls with a carbon mast. New examples of the VWM Blade and Stealth, and the Oz Blade were close. As has already been revealed, the Viper weighed in at 137kg, but I wouldn't take that figure too seriously. The boat was pulled together quickly for the event, and a I believe that more components were pinched off the F18 than is planned for production boats. If you want full details on what production Vipers will be like, get in touch with AHPC.
Paul