The (aluminum, I have no experience with steel) control arms do not break, if you care for them correctly. You DO need to inspect them for each session - if there's ANY play in the ball joint, you change the arm.

I think most of the failures are the result of lowering to the point of the ball joint being bent past its normal limit (you fix this by not lowering the car that much), or by the use of a very big sway bar with stock (or the like) springs.

I never had one fail catastrophically, and I once finished a three hour enduro with a loose ball joint...

YMMV, of course.