For me it is more in execution than just the materials themselves. You can have all the kevlar you want but if it is cured improperly it will not be "bullet-proof". And having a well thought out layout. Not a 9gal waste tank with no way to install a larger one other than starting to cut up the liner (not to mention the liner itself). No open transoms of any kind, incl. drop down swim platforms.
My beef with today's "offshore capable" boats is not the materials as much as the design and execution with an eye toward making a charter
happy boat which the charterers later will consider for ownership
. Or sooner rather than later.
Or how about those 7 step companionways without hand holds nearby? Real offshoreish, no?