FWIW... anecdotal evidence:
I have owned three "serious"
boats over the past 35 years or so
1. Yankee 30, built in 1974, conventional solid grp layup.
Sold when it was about 10 years old. No blisters ever.
2. Palmer Johnson Standfast 36, built in 1974 too. Some sort of MIL-spec polyester resin, foam cored
hull.
Sold in 2004 at age 30. No blisters ever. Just talked to the
current owner who has recently completed a major
refit... still no blisters.
3. Jon Sayer designed one-off, built in 1990. Strip planked Western Red Cedar in epoxy with e-glass inside and out. No blisters yet at age 22.
Point of all this is that it is simply not true that all frp hulls will have blisters, and that other materials too are immune to the pox.
But it is true that a great many boats have had the pox, including some from the highest end yards... like Swan, like Halberg Rassey, like
Oyster. It is a bit difficult to predict which ones will suffer and which will not... I certainly couldn't do so, so I think that I have been pretty damn lucky!
Cheers,
Jim