For years I have had one of those lifevests that inflates from a CO2 cartridge. I read that they now have vests that self-inflate if you fall in, even if a medical event or accident renders you unconscious, preventing you from pulling a cord. When I made an inquiry about these at a fly fishing shop, the owner said that he only carried the lifevests where you have to pull the cord, because he had heard of the self-inflating kind being set off by a heavy rainstorm. Does anyone have any knowledge or insight about the practicality and usefulness of the self-inflating vests? Thanks!