"Serge" wrote

Where is the catch?

The "catch" is that if you are knocked upside the head by the boom, neither the
CO2 cart or the manual inflation tube will be doing anything -- they have
negative buoyancy when deflated...

A more-expensive (and possibly not yet USCG certified) option is a hybrid, which
has some inherent floatation as well as the air chamber.

I use the inflatable on my 21' sailboat and when rowing in sheltered water.
Otherwise, a regular vest is preferable offshore or in bad weather.