Princeton Tech is a company that makes diving lights. If any major manufacturer knows how to make a waterproff headlamp, it is them.
But you said price is not important, so you may have to do some digging, but come up with something better from a specialty company.
My comments on the Vortek, Solo, Matrix, Predator, etc. (all essentialy the same light) are it is a pretty low performong light. It has the mechanisms complex enough for focusing, but it does not focus. The hot spot is blinging up close, but has rather poor throw. Side spill is not very usable with the hot spot. I can't imagine diving with it and having it all reflecting back at me.
I do like how modular it is, though. You can change out lenses, reflectors and bulbs pretty easily and there is a good amount of junk avalible. I even have a re3d lens. The bulb is a PR based, so they can be had in any power you like and are avlible anywhere. I keep a 800 ma bulb handy, but usually run the 500 ma it came with. I have a 1.3 amp bulb which I rarely use. Oh, I have a Solo, which is the 2 aa model. I seldom use it, but it was my first headlamp.
It makes a great loaner with the 400 ma bulb. It is one of the simplest and most rugged headlamps on the market. Quality of construction is very good, just performance is a little weak.