The idea behind the project is to try things out, a learning environment if you will. I make sure something works the way that I think it will, before installing or initiating on the actual domain. That way I figure I can iron out a lot of the creases without disturbing the users, or the servers, too much.
suppose the only down side to that would be you would have to not have it in the same IP range as your main network.
I'm guessing though you would of already thought of this and you wanted to use a different domain but with the same config.