This sounds pretty cool but tbh, if I'm willing to try out a beta product with all my images (and the risk of losing them due to some bug or any other risk) and provide feedback, I'd like to have a bigger carrot than just using the product for free in beta only :)
Fair enough. I've suffered from so many bugs in commercial software that I made some design decisions at the beginning of the project, in an effort to avoid more egregious faults.