I used Lunar for a week, then decided to remove it and go for Arch.
While I liked the moonbase, and the ability to just "lvu what" to check what an app is/does before you go ahead and download it, but I had two problems:
1. As you mentioned, it just takes too long to install. It took me 3 hours to install XFree86 on a P3 500.
2. the moonbase doesn't have that many applications, compared to RPMs or Portage, or even pacman (which is much newer).
With Arch, you can get an up-and-running system in 30 mins (on that same P3 500, without X though), and it is an i686 optimised, so you won't get that much benefit of compiling something by yourself and waiting for hours.
You can also think of Pacman ( Arch's package manager ) as a moonbase, it uses a similar concept on updating a list of available packages from the server, and then compare it to what you have to see if you want to update anything. It will also try it's best to resolve any dependency problems.
If you like to see more about source-based distros, http://www.distrowatch.com/source.php