You will find that there are about a dozen manufacturers making good products and each one has a full selection of models.... why? Because there is no perfect detector to use everywhere and in every situation. Some are set up as a more general use machine and others are specialized for specific hunt conditions. One of those specialized conditions is a salt water beach, due to the wet (potentially) conditions and the unique way it usually effects detector performance.. That's one of those places where people generally want a sealed, waterproof detector that will detect targets filtered deep in the sand. Electronically it can be a challenge for manufacturers to get a machine to work well in those conditions. Some manufacturers have overcome this by utilizing multi-frequency technology (which can get pricey).
The AT Pro is one of the most popular general use machines... it works very well in most conditions like inland and away from the beach. But being a single frequency detector, it isn't set up to sense targets as well in comparison to specialized beach machines in the salty beach sand. But that doesn't mean an AT Pro will not work at all at the beach... it's just not optimized for those conditions. As a first detector it will work just fine though and is often recommended to new users.