When I owned a scuba shop, I would try out new equipment that I sold or was considering selling. I had, more than once, both hose and hoseless air pressure monitoring devices fail during dives. As a boat captain, I see these devices owned by my charter customers fail all the time. In the thirty-five years I have been diving, I have had mechanical SPG's spring leaks, leaks in the hoses, suffer broken face plates and just flood for no apparent reason but I have never had one fail to give me a reasonably accurate reading of my gas pressure during a dive. Even when broken, a mechanical SPG will still work until the internal mechanism corrodes to the point that it fails completely. You have plenty of time to change out a broken or suspect gauge between dives. Why use an electronic SPG when a simple mechanical one is so reliable?