I have an engine analyzer in my twin, and it is extremely useful for
monitoring CHT on those hot days, as well as finding out the bad plug that
occasionally occurs on runup. I always run LOP in cruise, and can generally
get down to around 25gph at 8-10k and 174KTAS. I need to adjust my GAMI
injectors, since the cylinders all don't peak at quite the same fuel flow.

It may not be as useful in a 172, but for IO 470's or larger an dngine
analyzer may make more sense. On the other hand, I also have an AEIO 540
Lycoming, and even without GAMI injectors, the engine peaks symmetrically,
probably due to better fuel flow in the Lycoming versus the Continental.