You may need a subscription to open the following link, but Practical Sailor noted some issues with Spinlock that I was not aware of.
http://www.practical-sailor.com/blog/Report-Cites-Problems-with-Spinlock-Deckvests-11226-1.html
Does anyone have an opinion based on experience about wearing non inflatables for rough or offshore conditions?
As someone who uses deckvests all the time, I was of course interested in that. In 2013 the raceboat Uncontrollable Urge lost her rudder at night in big weather, and went aground on rocks. People died. Not a pretty situation at all.
I personally spoke to the person who chaired the US Sailing investigation. The conditions when the sailors when into the water were horrible, survivors likening it to being in a washing machine, with large boulders. Several of the sailors wearing deckvests had one of the air bladders (and strap) slip over their heads. Due to the nature of the event, it was not possible to tell when this happened, and in particular if it was before or after the blunt force trauma and water ingress that killed the sailor.
The one thing that the investigation could not determine was if their sailors had their straps tight. This is KEY for ANY vest system, and perhaps the deckvest even more so. In later testing, neither US Sailing, Spinlock, or any other organization could cause the strap to come over when worn properly.
We'll obviously never know exactly what happened. But in my mind the Deckvest is the safest, most comfortable, and most complete system for surviving a MOB situation made. The fact the the Volvo and Vendee teams use them as their personally selected MOB vest says a lot as well.