During dives in the North Sea off the Belgian coast, the Venture Heat is always taken along to be used during decompression stops. As a matter of fact, I always put the vest on during dives, it doesn't take up any space and that way I am sure to always stay ahead of the cold. The nature of the technology used by Venture Heat, namely infrared, makes it particularly pleasant to feel the warmth during long dives. I am also convinced that it will benefit my health in the long run.
I had had a drysuit, on loan, since 1983. Everyone laughed at me and called me a 'wimp'. But even then I was convinced that cold is bad for you and hypothermia is a big danger. I was allowed to borrow a Venture Heat vest and didn't want to give it back! Because even though a dry suit protects well against the cold water, there's really nothing to keep you warm. This is why the Venture Heat vest is 'indispensable' for me.
I found the biggest surprise of the first dive with my Venture Heat vest was that my hands and feet got much less cold than usual. Because of the heat on your torso, your blood flow is better and that makes a big difference to the wind chill of your hands and feet. I also find the difference in 'recovery' after a dive a big advantage of diving with my Venture Heat vest.