I paddled Westwater at the end of last season and had heard about the PFD checks. I just bought a Stohlquist Ed Lucero PFD which is probably the safest PFD on the market, but it is not Coast Guard approved.
(Stohlquist says it is too expensive to submit for approval such a low production vest, but I wonder if the armor plating might also be an issue for USCG.)
Anyway, at the put-in, I had my Stohlquist Brik available if they checked closely, but I had plans to put that one back in the car discretely after the check and use my safer Ed Lucero PFD.
They did only the mildest of checks, looking at breakdown paddles and the like for the whole group. I was never personally inspected.
I am not a big fan of flatwater anyway, but if I ever do return to the long suffering journey called Westwater, I will use the same switcheroo plan with my PFD's in case the inspection is more thorough next time around.
If you are interested in reading more about the now discontinued Ed Lucero PFD, there are comments about it in the latest uploaded entry on my kayaking web photo journal. An elaborate PFD specific journal entry is also on the way.