The Marstrom A Class hulls are famous for their strength.

According to the Marstrom website:
The M18 uses the same hulls from the A Class,
Is 2.5m wide, instead of 2.3m,
The mainsail is 15sm instead of 13.94sm,
The boat weighs 78kg instead of 73 kg,
And of course it has a 15sm gennaker.

I doubt if Booth would even have tried to build his boat without checking every single modification with Goran Marstrom.
Supposedly the ICCT boat was made fron the same hulls and hardware with an M20 mast.
The hulls didn't break.
The mast didn't break.
The daggers didn't break.
The rudders didn't break.
The hardware didn't break.

I think the issue of strength has been resolved.