I haven't broken a shaft or a tower but I did break the plastic ball cup on the bottom of a shock last week. The shock popped off the ball at the tower and I believe it swung around and got caught under the car. Luckily I had a spare plastic shock parts kit so it was an easy fix.
I do have spare front shock shafts though and I plan to pick up a front tower when I catch one in stock at Tower or amain.