Ok, i have never used on in water but it is my understanding that they are waterproof.
I would go as far out as you can wade in known swim areas then. I say that because most beach hunters (that I have seen) play in the sand. I have only beach hunted from time to time.
Sorry, I wish I could say more, but I don't know much about the AT Pro.
There are a lot of beach hunters here and I am sure they will weigh in. But you have a great all around machine there.