I use the Vaquero, most of my hunting is all coin, jewelery and relics. There are very few negative things I could say about the Vaquero. It is awsome on clad, picks up gold very well, and after months of looking for a more powerful machine in the depth department, I have realized that I already own one of the very deepest unless I want to spend big $ on a GPX.
Seriously, I have read biased review after another on the AT pro, and I am sure it's a good machine but I have already done with my Vaquero+more what people brag about in the reviews.
If I threw my Vaquero in the lake I am sure the AT pro would have the upper hand, other than that it is hands down Vaquero.
Sorry folks but my vote goes to the Vaq, if you want a water machine, I feel a dedicated water machine would get you the best results.