I bought a Summit in June and before even turning it on went brushless with a MMM 2200kv combo running 4-6S lipo.

It's been sitting for over a month now with the stock stuff in it again because I am trying to sell it.
But the only thing I ever broke was a ring gear in the rear diff. One of the driveline pins is falling out but tape and a rubber band holds it in there well. The trucks are tough but you MUST remember to never shift anything while giving it power. Diffs only engage/disengage when still.

Mine currently looks like a Revo (wheels/body/wing) but has a brand new motor, extra parts, and a TQ4 2.4Ghz radio. I am looking to sell it all for CHEAP. PM me if interested.