[Sneeck]

The metal idler pretty much make's the gear's bomb proof. Like you said you'll be snapping either those pin's or the complete input axle next.

There is only 1 really good upgrade, and that is the ultramaxxed tranny gear's. But those are rare and very expensive if you do find some. And heavy. I'd get a metal idler and stick a nail thru the input pinion and bend it to secure it.