I've never really thought about snacking while swimming. As a former competitive swimmer, I don't think I've ever really seen anyone eating anything while swimming...sometimes people would keep a bottle of water on the side of the pool, but that's about it. I use sports beans mostly when I'm looking for endurance while riding, and while swim practice would often run 1-2 hours, I don't really see it as the same type of endurance as biking. Think about it, if you're at a meet swimming a 500, you can't really stop in the middle and eat some sports beans.
It's only worth it if you're having fun