I'm very surprised by all this talk about USCG and other official requirements/ approval.
I agree a life vest does hamper my maneuverability in the water.. the few times I have been there with a capsized boat.. I would have been better with not having it... on the other hand if I was incapacitated I would be glad that it is on..
With regards to the USCG requirement... as I see it, it is all about "liability pass through." If I had a shop I wouldn't even think about selling a non-approved PFD...
There are also laws the require one be aboard the vessel for each person... you don't have to wear it, it just has to be there, unless you're under I believe 16, then it has to be worn. But like seat belts, why wouldn't you use it?