I agree that with skill you can get away with small boards. I'm 68 kilos and have spent lots of time with sub 65l boards as my biggest wave board and that has incuded some VERY light wind sailing on Maui. Now I would say that with only an EVO 70, I can be within 95% of max performance in at least 90% of all possible wave conditions and handle the rest 10% OK too.
That said, I've grown to like to sail bigger boards too. When the waves don't give you enough drive, I nowadays choose a board so big that I still have something to push against rather than just fiddle around on a small board. I've sailed the Aero and EVO 91, but for me, the EVO 80 is pretty much as far I need to go. So, with this in perspective I can understand that a 90kg guy would want something bigger too sometimes. the E80 for me pretty much coincides with a 100l boarf for a 90kg guy.
We had an unusual nice light 5.3 cross off day in Sweden the other day. Very hard to find speed, and while I could have been on the 70 or 80 and probably even gotten the occasional wave on the 62, the 80 was the perfect weapon: