I ran a custom Sq. top main on my N6.0na.
Was made by a loft Clear Lake TX. (Houston). Forgot the name.
NO problems with the Sq top and a chute on it.
Well- the orignal mast did invert once- we loosened the diamonds and bent it longways back again. Worked again for years. Until one light/moderate wind day with only the main and jib up, one of the spreaders broke. The mast didn't break, but it was totalled after that one.
FWIW- it'll handle a Sq top. And I ain't Randy S.

You're still sailing a 6.0? Cool

** Just realized that's my old 6.0 with the original pin top in the Avatar.