Depends on the beach and the level of mineralization.
I tested the AT Pro on our Central Florida beaches for Kellyco not long ago and was able to stabilize it pretty well. You have to properly ground balance in the environment you'll be detecting and then adjust sensitivity. In other words, don't ground balance on the dry sand and then go into the surf without ground balancing again. Same goes for the wet sand. Always re-ground balance when you change locations.
The ATP worked fine for me under those conditions. However, given that the ATP is a single frequency machine, using it on other beaches or areas that have far higher mineralization levels will degrade stability and overall performance.
Just the report from my foxhole. Your results may vary under different conditions.