Under extreme accidents, the only parts I've broken so far have been...
1 x Front wishbone, the point where this broke has been revised on the D4 Worlds car.
1 x Front gearbox top. Even though it broke, the car stayed together to finish the run.
1 x Rear hub. The ball stud pulled out of the side. Resolved by running longer bull studs, and now running the Ali' 0* blocks.
Apart from that, the car has been strong as an ox.
As for other peoples experiences..
The outer hinge pins do seem to need the grub screw tightening more than you think, but once done it should be a fit and forget part.
I've seen a front shock tower go, but it only de-laminated and again finished the run easily. This part has also been revised on the D4 Worlds car.