Sounds like everybody has had a different set of experiences with plastic vs steel spur gears. Not surprising though. Here are mine...

My experience with steel spurs has been (when running the typical electric direct drive setup) eventually the narrower metal spur gear pounds a dent into the wider pinion gear. After a while, the spur will want to wander back and forth within this "dented groove" and sound like a broken blender. Noisy as hell! Which is fine if you don't care for the ability to listen for other audible clues of vehicle malfunction. This happens because the pinion/spur interface is where all the change in forces/direction takes place (going from forward to reverse for motor braking and then back to forward). The constant gnashing back and forth at this focal point will eventually destroy the pinion and spur both...just depends on the weight of your vehicle, tracks you run on and how aggressive you drive as to how long it takes and when. I was going through two pinions ($12-$15) a month and one spur ($25) a month...racing every weekend. Pretty costly in my mind.

So...I switched to plastic. The kyosho plastic spur is inherently quieter because of the material and since it is wider it distributes the forces across a larger area and does not cause a dent in the pinion...hence no wander and the pinion never gets trashed. However the spur will eventually go...and usually in a sudden catastrophic way. Not good in the middle of a race. The up side is that plastic spurs are CHEAP...20%-25% of the cost of a metal spur. I was getting roughly 4 times the run time out of a kyosho spur ($5) vs metal spur with zero pinion wear. Pretty good return in my mind.

Then I started using an electri-clutch / traktion drive AND mechanical brakes on my eBuggy with steel pinion/spur (as the plastic gear was too wide for the braking setup). Since the forward/braking forces are no longer focused at the pinion/spur interface (clutch eases power delivery and they are both just along for the ride during braking) practically ALL pinion/spur wear ceased. It runs much quieter now and I have yet to replace either component in the drive train. This was 6 months ago. Excellent results...identical to my nitro.

Some of you have probably noticed something quite similar.

There you have it...my contribution.