Balancer 101:
A. Always use red loc-tite when putting bolt back in.
B. Any warranty on the crank is voided if it's been pinned and then get's damaged. (crank is around $4000 not including labor)
C. Check your balancer pulley every once in a while when the car is running, if it's loose you'll see a slight wobble.
D. The crank seal leak is normal when the balancer falls of, it usually get's damaged or allows oil to pass by since the balancer hub isn't tightened down on top of it.
E. The crank is a very, very, very, hard piece of steel. In all likely hood you would damage the balancer and the belt before you damage the block or the snout.
These are all just from my experiences, my balancer has come off three times. Two of them were with pin kits (Roll pins were sheered)
Good Luck,
~Matt~