I have successfully integrated X-Cart and aMember together. You can see this at http://www.jazzpianolessons.com. The way it works is that when a customer purchases through xcart, they receive a download link that adds their information to the amember database. I did it this way because I had no idea when the new release of amember is coming out. It is has been "coming" for over a year now with no real news of when it is being released. Also, I think xcart is a more solid shopping cart with many mods and addons. Anyway if anyone is interested you can contact me here. Just mention xcart and amember integration.