So, auto-inflation is a neat mechanism. The needle that pierces the CO2 canister is springloaded and restrained by what's essentially a salt tablet. Immersed, the tablet dissolves rapidly and the spring drives the needle through the seal.
Downsides are that if you are hammered with a solid spray from a wave, you could have an inadvertent inflation. One reason kayakers generally don't favor them. And you need to replace those tablets on a regular basis. Leaving them stored in a high humidity environment can cause the outer layers to harden into a crust like you find in a salt shaker, meaning it might not dissolve. One of my recent projects at work was an air dropped SAR kit that incorporated some of these in about four places in the kits. Placing them into the humidity chamber out at China Lake proved that out. After enough exposure, those fittings failed to actuate when immersed. At least for a while.
Like helmets, I think you shouldnt be required to wear them after a certain age, but if you choose not to, you should be liable of the increased costs of finding/fixing you. And carrying increased insurance for that added risk.
