How many btc have been transferred in orphan blocks, but then never included in any later block? How many btc have been transferred in zero-confirmation transactions that have never been included in the blockchain? How could one find this info?
This would be an upper bound on the amount of fraud done by reversing transactions.
The first is an upper bound on the amount of fraud against people who wait for 1 confirmation, and the second is an upper bound against people who don't wait for any confirmation.