All right!:) Cheers for your reply.
I don't believe UX designers will leave paper. We are not using paper now because we have bad software, we are actually using paper because we sometimes want to keep ourselves away of computers (tablets counts as well).
90% of UX designers use paper (according to research by Todd Zaki Warfel).
Adobe learnt that recently. They did app very similar to yours and didn't succeed much. Personally don't know single UX designer using it. And they put a lot of money into marketing.
http://www.adobe.com/products/proto.html
It looks shiny and cool, but it's useless in UX design process.