Since the Vaquero and Cibola have the same basic electronics you should have the same result with a Vaquero.
Using the standard 8x9 coil I can run the Cibola pretty much wide open on wet and dry sand. One freshwater beach I went to had some black sand and I had to back off on the threshold a little but the machine ran smooth with sensitivity all the way up.
A couple times I have waded out into shallow water with it and, surprisingly, it seemed to run smoother with the coil submerged in water. I can't explain that.
One nice thing is that I find really tiny stuff with the Cibola. Itty bitty pieces of foil and copper give a strong signal. I bring a plastic cup when I hunt so I can scoop up the tiny stuff that goes through my sand scoop and run the cup over the coil, empty out some sand and repeat until I have the target.
Most people would think that's annoying but I know I have a good chance of picking up small earrings and chains because of the sensitivity. My Excalibur won't sound off at all on the small targets I find with the Cibola.
I think the Vaquero would be an excellent, fresh water beach machine.