This looks like it work great for optimizing/consolidating personal cards, but one advantage Coin offers is the flexibility of charging normal purchases to a business account. I'm not sure how Wallaby could discriminate if my restaurant meal or office supplies are a business expense or just personal use.
Either way I'm all for any innovation that thins out the number of cards in my wallet (with the goal being zero.)
True. But it would work with all of your personal cards, which is the main proliferation problem.
You could use them together. Get a Wallaby as your "one" smart personal card, and if you feel like springing $100 to go from 2 cards down to 1, you've got Coin.
Personally I'd be a tad worried about handing my Coin to a server to charge a big business meal. What if they accidentally tap the button and switch to my personal card when they're holding it?
Either way I'm all for any innovation that thins out the number of cards in my wallet (with the goal being zero.)