The services on the official registry are manually tested and verified by Start9 engineers. There's a delay between software releases and when they appear on the marketplace, but you know it has been tested very well by Start9 staff. If you like to live on the edge, you can always fork and build the service yourself. (I do this, to help out start9 testing new releases or when I really want a new feature before it's officially released).

This is no different then the "apt" repositories on linux. A lot of software have newer releases, but the official repositories are always a bit behind, because... testing, stability and security.