I have a very worked supercharged A15. Numerous friends of mine (Who are lunatics in their own right) have often made exclaimations about how mercilessly I treat my driveline. They are getting old now, (The "H" pattern 60 boxes are slightly newer than the dogleg 60's) but providing they have tight bearings etc, they are pretty strong. When they get slogged out, they could well be more susceptible to torque induced failures.
And remember that in the 60 boxes, the H and doglegs are of equal strength.