"It is ridiculous to judge the board's capabilities from video of someone who is not a competent rider on that board and is making serious elementary mistakes."
Precisely, so why use the video as an example of how the board performs?
Absolutely incorrect my videos show many turns, these are accomplished without fuss and without standing far back on the tail. The boards turn from the trimming position.
Spray throwing is an inefficiency, ideally all turns would be accomplished with the minimum of spray.
Wait and see... at present I'm producing a smaller more highly rockered version of the Makaha called the 'Hotkurl' with a deep single concave and a relatively high angle of lift on the tunnel. This design is not new to me but is to you. It's a winner... very fast and nimble.