works if you have a watch (probably the master plan to increase their sales?)
A change of UX would be on the cards yes, but the way you describe it just slows it all down. at the moment the software knows if the phone is near the RF reader and flips to the wallet and detects your fingerprint without me having to do anything apart from resting my finger on the home button.
I've only paid once via the iPhone, as I always use AW.
I agree on the fact that it would be quite slower than touchID, but still usable in my opinion and better than a card since you don't need to enter the pin.
The convenient stuff about using the Watch is you don't have to reach for your wallet or iPhone and that would be great on the tube because taking the wallet or the phone off your pocket in a crowded place is less secure than simply tapping on your wrist. If only the public transit in Milan would support that...
I guess on the tube something like the oyster card will always be faster than an iPhone, but as I said the Watch would be even faster. Too bad is not widespread as the iPhone