Thank you Cap!
The following is anecdotal evidence from one of our crustiest engineers. (Take with a few grains of salty ceramics?)
Gas loops are prone to false alarms, says he, due to their sensitivity and the placement calibration, but are less likely to fail a BITE test. Inconel (or capacitive Kidde) loops are fragile and can be a pain in the keester (his word) to install unmolested, however they tend to produce fewer false alarms.
Our guy was unable to say definitively which loops are installed on which airplanes, but I assumed the gas loops are on newer NGs and the Inconel goes all the way back to the Jurassic, but do not know this to be absolutely true.
Any chance you might? Cheers!