I've had two pairs of Burton Hails, so I don't really know too much about the ION, but from what everyone that has had a pair says, they love them.
Any boot by a major snowboard brand will keep you dry. Like everyone else said, try on as many different boots as you can, and get the best fitting, most comfortable, regardless of price. Boots are the most important gear you will buy. If they aren't comfortable, you will be miserable.