With good network health, we have confirmed transactions at 1 block and I remember reading something by bytemaster on why this was ok (it was related to forking and probability), but if you think about it, 1 block is 1/101 of the network signing off on your transaction.
After 51 blocks, 50% of the network signs off on your transaction, which appears at first glance to be the amount of time you'd want to wait in a trustless system - so if bitshares were trustless, would we be waiting 51 blocks for a confirmation?