As long as we're bumping necros...
(That sounded better before I typed it out)
My view is that inflatable PFDs work "most" of the time.
Do you really want to be on the short side of that stick?
On lakes, I don't care as much because I figure that if my inflatable PFD doesn't work, I usually will have at least 1 filled bladder that I can use to kick to shore with... and yes, I've gone fishing with a slow leak and had to periodically re-inflate my bladder... but I was more flexible back then.
FYI: belt PFDs usually inflate to look like a yellow version of the cheap orange PFDs... so you still have to put it on after inflation.
If I'm in a harbor, in saltwater, I know I can still probably make it to the harbor edge in a deflated float tube, but I also know I may have to go a long way before I can get out of the water, especially if it's low tide and none of the docks have a ladder. Don't ask.
Trust me, if you've got water in your waders you won't sink, but you will have a hard time even getting up a ladder much less trying to muscle your way on top of a dock without a ladder.
This is why I prefer a kayaking PFD if I'm on saltwater, and especially if I go outside the main harbor... I don't often go outside the breakwater, swells in a kayak is one thing, swells in a float tube is something else... And I've seen someone get flipped.
Why a kayak PFD?
It doesn't write up against the front of my neck, and the back padding tends to accommodate being in a seat more.
I always carry a whistle, because just like cars boat drivers don't see anything except other boats.
I use a pea-less whistle and I can always trill my tongue if I want to make it sound like a regular coaches whistle.
You'd be surprised at how surprised people look when they finally realize you're there, even if they're on a paddle board.
Especially if you use an air horn (you can make those refillable if you have an air compressor).
An auto strobe is actually fairly inexpensive and quite small.
If you do get an inflatable harness or belt, and recommend wasting a CO2 cartridge every so often just to make sure it works.
If it's a standard CO2 cartridge, they're much cheaper if you don't buy them at West Marine. Big 5 has them, Walmart should have them, Amazon has them for sure.