I prefer PET as well but it is not as rigid as PLA.
My machine, PLA, was built more than a year ago in humid San Diego, very near the ocean, and now I am even closer to the San Fransisco bay. It ran almost continually since the day it was built. I wholeheartedly do not believe such a young machine had issues with humidity. Many mornings this winter I had my machines with an under temp warning which means they experienced temps under 5C. I would warm up the bed and extruder with a heat gun to over 5C and get them started again. I have been intentionally beating up these machines looking for obvious issues.
I am not sure what could have caused your issues. What is your conduit measuring?