CP1: Even with a payment processor like Bitpay, if the money is unconfirmed it will never make it into the ledger.

Sonny: Someone from another forum posted:

"blockchain.info can't undo transactions. they can only let you attempt to double spend them and stop rebroadcasting the old transactions so they might disappear from the network before they get included in a block, but I'm not sure if this happens."

So, will blockchain indeed stop broadcasting these after a few days?

If not, I found a potential solution here, which is something that looks like a real pain to deal with:

https://bitcointalk.org/index.php?topic=231057.0