I didn't respond to the survey as I try to attend vintage equipment gatherings each year, and dive using my vintage equipment as often as possible...
As chance would have it, I live in one of the most active areas as concerns vintage divers in the country, Southwest Ohio. Serendipity is a wonderful thing, but if you try to analyze why would there be so many of us in this area, you'd just scratch your head and give up, there is no logical explanation. That said, there is a great crew from all over North America who participate in our little corner of the scuba diving community. I encourage those of you who haven't yet attended a vintage equipment gathering to do so, we are a friendly bunch who welcome all like minded divers - those who see beyond the "must have the latest and greatest" mantra so common in our sport, and see the value of the pioneering efforts made by US Divers, Voit, Healthways, Dacor, etc.
One common point of reference seems to be that nearly all of us became fascinated with scuba through exposure to either the televised Sea Hunt series or The Undersea World of Jacques Cousteau, programs that promoted underwater exploration, while featuring double hose regulators and minimal amounts of other equipment. Some of us have been diving since the days when the DH regulator was the norm, or at least, since it was not uncommon to see one or more in use at a dive site.
For the new convert, or someone with curiosity and a C-card, I recommend that you approach the vintage equipment user when you encounter him or her, ask some open minded, open ended questions about their gear, and you will almost assuredly receive an historical account of their Mistral or Broxton, plus maybe even get a chance to try one out. A couple summers ago, I made a commitment to only dive my vintage equipment for the season. It resulted in at least five or six long conversations with divers of all ages, and the lending of my Mistral on two occasions.
Come by a gathering when you can, it is a great way to spend a day, or several.