I have used surface supplied (hookah) gear, in one form or another for many years. Until recently, I had never attempted to use an aquamaster via the hookah port. I did some informal (and highly subjective) tests using a industrial breathing air regulator for my supplied air. I opted to use an unbalanced aquamaster since utilizing the hookah port provides the intermediate pressure. The advantage of the large industrial regulator is that the IP can be fine tuned over a very broad range of pressures. I tried two regulators, one with a standard second stage and another with an HPR second.
I found that the HPR provided much better breathing characteristics across the board. This difference was quite apparent at lower pressures. I found that the HPR equipped regulator breathed acceptably well below 70 psi. Again, these were just my observations and by no means a conclusive test.
Btw, Simon beans still makes the excellent hookah harness!