region/carrier specific prices in navigator.mozPay()

Hi all.
For anyone tracking navigator.mozPay(), could you take a look at this price change proposal and perhaps provide feedback?
https://groups.google.com/d/msg/mozilla.dev.webapps/3B4CIXJFY1M/Q9NvBeae9aQJ (mirror of thread)
https://lists.mozilla.org/listinfo/dev-webapps (list info)

Up until this proposal, the price of a product was a numeric ID that the payment provider could map to a price/currency however it saw fit. This was nice and abstract/generic. The proposal above makes things pretty specific to Mozilla's Firefox OS rollout insofar as prices can be overridden per region / mobile carrier at the merchant's will. Maybe someone has ideas to keep it generic? 

It's likely that mozPay() will exist as a dumb pipe for incompatible data structures (like WebRTC) and that will be ok but it would be nice to avoid that.

-Kumar