Exactly right.
Here it is:
viewtopic.php?f=107&t=2387451
As I see it, FS Radical has more straight outline. To be fair, only after mega or giga hours of kiting (and not couch surfing! , one could purely benefit from a board.
But this would be so tiny benefit compared to ie handle or straps made for air style.
My reasoning about the performance/price with a DIY is: huge performance/ultra low price (or divide a board price/number of hours on the water per year - same for any piece of equipment). That is a cost you paying. If a higher cost makes you a better kiter, great. Whatever works. For you. But may or may not for others.
D.