And have they taken various security considerations into account, e.g. SYN floods?
I've been working on a similar program for a while called libgis. The main difference is that libgis is built as a library instead of an application and uses OpenGL for rendering, which allows it to render terrain. It also uses GTK+ instead of Qt, but that's just due to my personal preferences. Unfortunately, it's not (yet!) as complete as Marble/WorldWind/Google Earth.
But they're the project leader. They're calling the shots so you use what they specify.
Most projects let you pick your editor, filesystem, distribution, etc. It would be nice to add version control to that list. That doesn't seem like it would be all that hard to do. There are already tools to migrate a repository between different version control systems and they mostly use similar concepts.