I got Galloway's steel guide and spring kit. When I pulled the plastic one out, it wasn't really worn, just a little hammered looking (2000 rounds). I didn't see any cracks or indication that it would break but like you, plastic seems like it might break.
I put the steel one in along with the springs and got a little lighter trigger pull.
I also put a Galloway spring kit in my CM9 for a slight reduction in trigger pull weight;I thought while the slide was apart it made sense to put the SS guide rod in as well. happy with the Galloway kit.
NRA LIFER
IDPA BELEIVER