While I have tried neither at the marine shore, there are some inferences we can make.
The Vaquero would get the nod, in my book, as it has a GB to help with the wetted salts and mineralization pockets found at the surfline.
Both models would require some finessing of the DISC and SENS controls to manage the "chirp and chatter" one could expect. They are, after all, VLF machines. Less SENS and a bit more DISC would be in order.
Some consideration should be given to getting the bigger coil(s), in order to maximize the depth potential.
Triple bag the control housing - find a way to seal 'er up. While the coil is water proof, that's it. I'd suggest that if you are gonna spend alot of time around the surf, get a CZ-20 or Excalibur. Both can easily take a dunking as they are submersible - the Tesoros, no way!
In the dry sand, there would be no worries other then picking the right spot. With SENS out near max, the DISC a notch below nickle and maybe a little "SuperTuning", you'd have a deep, stable goodie-getter. Small gold wouldnt stand a chance.
david