Used inflatable PFDs on the flight deck always in the Navy. Never went over the side so I don't have personal experience with autoinflators. Given our litigious society, I tend to think they'd work just fine. But for a non-swimmer, I'd recommend the regular PFD. 100% reliable. They'll feel more confident, and that's important when they have a fear of water. My wife doesn't swim and I've seen her rescued at a water park when we were dating. Came out of a slide and was disoriented and didn't stand up. Water is no fun for non-swimmers. Make sure they feel safe, and they'll have much more fun.