I know I'm a bit late here but...
I just started rebuilding a site using ShopSitePro and so far I'm exceptionally pleased. Very easy to use, as
SEO friendly as you want to make it. The add on modules are really nice as well.
I decided to use folks at Lexiconn (
Web Hosting Solutions, ecommerce solutions using ShopSite, managed dedicated server hosting) for hosting. They include some really good add on modules. Additionally, their support is outstanding. I don't say that lightly. Tech support answers and help in minutes. They know ShopSite cold. You can sign up for a ShopSitePro demo to check it out and play with through them as well.
Dave