I won £25 for a GEMS back in the '90s, so no - it wasn't just for engineers!
I submitted another suggesting that the proposed JTIDS system for the VC10K should use the aircraft's new EGI system for aircraft position and time, rather than the standalone GNSS which was on the cards at the time. Which saved £LOTS - and was eventually adopted into the architecture. But my GEMS was rebuffed.