Another thing you might consider doing to increase conversions would be to have an explanation about Blockchain pop up when they hover over that part of the sign-up process - explaining that Blockchain allows you to use bitcoin without having to install the bitcoin software on their computer, and that they will have to verify their email with Blockchain etc etc.

Your system is a fun way to introduce people to Bitcoin - most of them have heard of it but have no idea how it works, so some hand-holding and empathy would go a long way to improve conversions.