I would agree with Labatt. For dingy sailing find something that likes to get wet that will save your life if needed. An auto inflatiable is a big shock when it goes off when not needed. Been there ...did that.
However, my grand daughter thinks that our auto inflatables are great. Sne likes the comfort when on board, and loves testing them every other year when I push her off the dock. Best of both worlds for her.
It's simple for me: Am I alone or not?
Alone in the Zodiac? Full vest Mustang PFD...no gadgets, no cylinders. It's similar to what kayakers wear and yes, it's hot and it's heavy-ish. It requires neither my attention nor a magic pill to work.
In the Zodiac with crew? Manual inflate PFD. The lightest and the easiest to use when sitting on a pontoon.
Alone in the boat? The Stearns auto-inflate PFD with D-rings. I clip on in any kind of weather. I nearly fell off the low side once sailing solo in October in a 35-knot beam reach doing 7 knots with no PFD. Know what I was doing? Retrieving fenders that had rolled off the deck so I wouldn't look like a newbie! I was lucky I only lost some finger skin when I hauled myself up to release the mainsheet and not my bloody life.
With crew on the boat? Frequently nothing, but in more than 15 knots or 15 degrees of heel, on goes the PFD, either the Stearns or the Mustang inflatables. My five year old isn't allowed on deck without it, and no longer needs to be told (or to hear "one hand for the boat!).
One thing to be aware of: Auto-inflate PFDs are considered some type of explosive by the airlines, and you can't take the cartridges on board. I didn't have time to get a replacement cylinder in Portugal, so on my first salt-water delivery, I was essentially PFD-less (although there were plenty of floating vests aboard.) Next time, I'd just bring the floating vest.