I used to do something similar in another MMO and the program was very effective at weeding out both RMT and troublesome players. The downside to the program was that it was difficult to find players who had a true commitment to their duty. Many lost interest because it required going above and beyond, especially since it would eat into your playtime. There was a handful of us that stuck around though until real life reared its ugly head. Yes it was a volunteer role with an interview process (did have some perks as the GMs way of saying thank you).