I dont know the answer...
But I do know, that measuring with a weight doesnt make much sense, apart from getting a rough idea if it is superstiff or a mega sponge
As nobody wants a TT board that flexes in the middle - it will kill all the good characteristics of a good board.
Whereas quite stiff in the middle, but we want some, or a lot, of flex in the ends, works awesome.
For waveboards it is even more difficult, as here we want some flex at the right spot along the rockerline close to the tail, not too much either so it gets too slow and spongy - but even more difficult to measure or describe what works best.
So the "right" flex pattern is desired in all types, depending on what you want and use it for, and difficult to describe.
As stiff as possible is hardly never any good, except for racing or kitefoilboards, where low weight is also key