first off my expereince is s&g and not strip but I'm pretty sure that any failures folks have had from very light layups are not while paddling but while dropping, crashing, strapping, transporting, storing etc. Paddling is pretty low stress. Dumping on a beach, getting tossed in a rescue or dropping a ladder on a kayak is high stress. My take on practical low weight layups is that if you use light glass on the high wear/impact areas like the the bottom you'll have damage,,4oz isn't very ding resistant with 250lbs sitting on 1/10 square inch of rock. So you can use lighter weight elsewhere and find out if it's tough enough or not,,regarding structural integrity I figure anything that's going to crunch 4oz on the interior will do the same but to a lesser degree with 6oz. Basically you make it light and you'll find little things to repair, make it heavy and you'll find areas that never need repair and some still do. How you use the kayak will make the biggest difference.