One question -- why didn't you use the App Store? Was your decision technical, financial or both? I really appreciate the convenience of the App Store, especially for updates.
I've scribbled down my reasons for releasing outside the MAS here: http://blog.servus.io/post/37663343570/servus-1-1-grand-stor...
Regarding updating: Servus has a built-in auto-updater, so it's easy to keep it up to date.
Another benefit of the App Store is convenience. I don't have to type all of my info into yet another place. Can you get stats on how many people abandon the FastSpring form?
One feature request: resize preview images. My test png wasn't resized for the thumbnail and took a couple of seconds to load.