There are many thousands of these type gauges in use under many hoods. There are also many brands of varying design and quality. A good design and manufacture should ensure no leakage at many times the normal fuel supply pressure. I believe that those designed for use underhood and from a reputable manufacturer with good quality, should provide safe, reliable service. Mine is a Holley 0 - 15 psi, non-
oil filled, which I have had installed for over 5 years with no issues. I also run a fuel pressure regulator set at 5 psi to provide the proper consistent pressure and prevent the gauge needle from bouncing all over. We will never know the root causes of the leaks/fire events mentioned, but there are several possibilities (materials, workmanship, overpressure condition, installation issues, fuel additives, etc). I am wary of automotive products made in China, since I had a ProComp fuel pump fail within a year (then found out it was made in China). We all have our respective experiences and opinions, and I am leaving my gauge in place underhood (but I do check underhood for key safety items prior to every drive ( fuel leakage, brake/clutch fluid level, spinners tight). Good luck whatever you decide.