6 months and 4k miles and no complaints, mine is pretty quiet with exception of tire noise. It drives great and has been amazing for MN winter driving so far. Waited exactly 2 years and I would do it again.
I get what you are saying but from personal experience on a 2014 f150, spraying fluid film yearly there was zero rust after 7 MN winters. Avoiding undercarriage car washes during winter then using salt away in spring to wash off residue
spray fluid film and surface sheild using undercoating gun. Takes a hour each year. Sprayed 2014 steel body f150 every year and zero rust before I sold last year. Getting into frame rails and rocker panels is most important
Lots of discussion on forum about this topic, short answer is spray fluid film or equivalent yearly to undercarriage and inside frame and other penetrations