I can add one data point. we recently launched this app - http://burningmanapp.co/ http://burningmanapp.co/ - it converts your steps into bitcoins. the usage is

I can add one data point. we recently launched this app - http://burningmanapp.co/ http://burningmanapp.co/ - it converts your steps into bitcoins. the usage is really off the charts >1000 users logging around million steps everyday. >50% have provided their Bitcoin address.