I agree with Bill, the inflatable vest is not any good until it is inflated. Most of the time in a kayak if you are in a situation where you depend on the vest you likely need it ready right away, not to have to inflate it even if that just means pulling a cord. If you get run over by a boat and knocked unconscious (my worst fear) you won't be able to pull the cord. As for the auto-inflate vests once they inflate that's it. If you roll and it inflates then you'd have to wear it the rest of the trip inflated unless you carry extra cartridges... lots of hassle, and the inflatable vests are very costly. They are not cut for kayaking either.

I have a Lotus Designs vest that is specifically cut for kayaking and it's very comfortable. I wear it 100% of the time and it doesn't interfere with my paddling stroke or my spray skirt. It is very comfortable even on long trips of 5 hours or more. I will say it again, I ALWAYS wear a vest. You can check me on that. It not only keeps ya afloat in an emergency, but it also adds visibility. I recommend yellow or orange. Mine is yellow and has a reflective stripe that I always thought was for night-time but I let Amy wear my vest and as she paddled out a good mile I could see the reflective strips in the sunlight. I never knew my vest was so visible. I also wear a big white cowboy hat partly to keep the sun off, but also for added visibility. It's also an important part of my image. LOL