It is actually really easy now to run a server on old ren using the luatt plugin and making it so you can buy back buildings, or buy any vehicle, char, weapon or build stuff. If I ever sit down and finish mine, it already has all the features mentioned above.
Edit: St0rm ran a xp system before its ren branched died. It was enjoyable, but I would not recommend it for the whole game. Leave it to a clan or server to run it if someone wants it.