although I assume we would load the ECC version of the account number into the phone with a QR scan
For face-to-face transactions and point-of-sale with your phone, NFC for those that support it and QR for those that don't.
For web sites, transactions need to be as behind-the-scenes as possible.
I'm personally waiting to see what comes out of the Curve25519 JavaScript bounty. I think signing transactions from within the browser could potentially solve the on-line store problem.