I recall a thread about a Jag IRS shaft breaking on a road course, and the car DID roll. Driver was OK,,, got lucky I reckon. The way ERA modifies the half shaft, it can break, but it won't let the wheel flop around. Their methodology specifically address' the shaft as a control arm problem.
I don't recall a BDR thread about a half shaft breaking on a road course or Auto X, it seems to be limited to the drag strip. BDR's often run a faily low rear gear ratio (3.5 to 3.9 range), when you combine that with a T5 or TKO 1st gear ratio, and plenty of bite, you maximize the torque. That could be the primary factor.
The original 289 drag race cars were running extremely low rear gear ratio's, 5.13 or something wild, with slicks of course. They primarily had trouble with rear end ring and/or pinion breakage.
DV, with his Viper powered Classic Roadster DESTROYED a Ford 9" housing when the ring/pinion AND housing exploded, so anything is possible when your pushing the limits.
Roush? I wouldn't put one in my car if you gave it to me!
