BLE meets a different use case than regular Bluetooth. BLE is designed to allow always-on broadcast "beacons" which are conceptually similar to NFC tags, with very low power requirements. The tradeoff for this ultra-low power consumption and always on nature is the same as with NFC tags: you get very little space for data, and they are essentially one way. That's why a common use case for it is to trigger some other mechanism like a classical Bluetooth socket or HTTPS connection.

I think BLE has a role to play in Bitcoin payments, but probably not for actually transferring payment data. Rather, a merchant should be able to drop a BLE beacon in their shop, and then wallet apps can use that to learn where to download a payment request/upload a payment message. But the actual data transfer would still take place over Bluetooth, Wifi or the internet.

That leads to the question of what the beacon broadcasts. A bitcoin URI is the obvious answer: the problem is a URI contains an address. No problem for the "throw money at a live performer" use case but a problem for the cafe use case. If we are willing to mandate BIP70 and remove the static address part from the URI the we get a "uri that points to a url" which is a bit inefficient but at least lets us distinguish bitcoin beacons from other kinds. That still leaves the fundamental question raised by the Airbitz spec - how does your wallet download the right payment request?

Unfortunately that's a tough UI problem. I don't think comparing long hex strings manually is a good way to go. This seems less user friendly than a QR code.

Once we solve that problem, how BLE beacons can trigger payments will all fall into place. The tech part isn't the hard part.