Nobody said the double Hall switch was a good idea....
Vibration ? I thought BME engines didn't..
Heat ? We ran an engine all day long in Phoenix, AZ in the middle of summer, with the SINGLE hall switch epoxied into the ball bearing mount of my ignition..Temp about 105..No problem..And my ignition circuit is inside the mount of the engine, where heat would certainly be greater than the C&H, in a box in the fuselage, way cooler..All my sensors are epoxied in the the aluminum mount...
Don't remember wishing for anything....
Good luck to BME finding something better [8D]