Trying an experiment... I printed the right z-tops (and motor mounts) in PLA+, and printed the left in PETG. I'm going to check for looseness and wear at whatever intervals I remember to, and anytime I take it apart. I'll try to remember to report back my findings from time to time.
Thanks @pekcitron for the detailed work! I believe I'll be printing many of your designs!
Inland PETG and PLA+
Red and Yellow
Printed as instructed, except for material.