Dan,
These are great for work boats etc. to be used in an emergency. I do not know where and what type of paddling you do; however for kayaking where you can be dumped without warning in inhospitable or calm conditions I would not want to worry about blowing up the most important piece of life saving equipment. I want it to work immediately and reliably so I can work on other things needed to recover. As you know this is especially important during cold water paddling. Are you going to spend the additional $ to buy a dozen extra air cartridges for practice? Have you tried it on fully inflated; can you still paddle comfortably or at all? A couple guys use them on our boat but I have never seen them blown up. What happens if you become disabled or unconscious due to accident or illness; Bye, Bye Dan. Personally after twenty five years rescuing people on land and in the water I found that it happens fast; very fast and when you least expect it. For kayaking I will stay with old reliable. Of course that is just my opinion.
Good luck,
Timothy Mulherin