Why MATO is one of the only (certain Aus-based one does too *cough*hobbyhavoc*cough*) retailer that buys them pre-fitted with metal gearbox I don't know, as its literally only a couple of dollars more when buying direct from the factory.

Sure, metal introduces another possible problem (need to be broke-in for proper performance) it also takes away another problem, the slipper-clutch. I have all 3 - original orange-geared plastic w/o clutch, white plastic w/clutch and metal (w/o clutch) -- the clutch can kick in a ridiculous amount of times on a Pershing, due to the rear sprocket managing to pickup every piece of junk on loose ground.