Near as I can tell, the Pro Open's seem to be substantially heavier. Heavier layup in the hull? The Zodiac USA site doesn't exactly have a wealth of information.
A buddy of mine has a Pro 16 (15' and change, I think) with a Merc 60; he's run it for a couple of years now, seems to be OK. Some spider cracks around the transom; probably just cosmetic, as they haven't gotten any larger.
jky
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