It will be interesting to see how this experiment goes. I've always wished there was a way to test drive a theme before paying out the money for it. I've bought several themes in the past where the demo looked great, only to discover it was very difficult to set up, or I couldn't quite customize it the way I needed. So spending the money can be a risky decision sometimes.

I don't know if there is or will ever be a way to offer a test drive without giving it away for free as you've done. Hopefully people who test drive this theme will be willing to pay for support, and/or get a taste of what your other themes are like and consider buying those.

Good luck!