The best thing to do is try it yourself, near the shore. Let out air in one or two of the chambers and see how you do. This exercise will give you a lot of confidence and good experience just in case it actually happens. Whether you carry a pump or not probably depends on how far away you're going. It's bulky and you don't want to loose it. It would only be useful if 1. you have a leak, 2. you are able to successfully repair it in the water, and 3. if you actually need to repair it on the water. With the i-12 I could stay afloat and operate the Drive on any one chamber, but then it has a larger volume per chamber -- also may depend on your weight.

If you do take the pump with the expectation of using it on the water, your practice will come in handy there too. You have to sit near the inflation valve to use the pump which makes that area low in the water and potentially awash. There is a way you can hook your leg / foot around the inflation area to keep it from giving way while pumping. Experimenting on how best to do that is worth its weight in gold if you ever have to do it!