I'd def love this feature.... sync it with a pre-paid card (to prevent major damages in the event of theft) and I'd be all over this.
How does having to constantly go an add more funds to a pre-paid card make it more convenient? Does not a credit card (which has protections against fraud, anyway) provide the same loss minimization with credit limits?
Does it really take that long to remove a credit card from your wallet and swipe it? A lot of stores don't even require signatures anymore for purchases under $50.
The fact that it could avoid signatures and ID verification is interesting. But it's not that convenient if you have to turn on the "transmit CC rif" every time, nor does it seem to be a good idea walking around with your phone broadcasting your CC info, no matter how small the range and encrypted.