Alex is right. We might have hit the wall already on race board width.
I have a good feeling that 70 cm as a max width would be a great place to limit race board width. Right now a board on or close to 70 cm will just work well in light wind only, and when it is 9 meter weather you will be lucky to make it back to the beach. I do not see 70 cm being a problem for big guys as well, as far as being too small.
As Alex already mentioned, a big kite racer like Sky Solbach can easily get the performance by using bigger fins, wider tails, more volume an a flatter rocker line if he needs more light wind performance. 70 cm is plenty to get him up and running.
In fact it's overkill on width; it would be the equivalent to wider than a 100cm formula board, in relative terms.
Let's keep the discussion open and see where it takes us, but 70 cm is massive wide!