We have taken several VIP tours - 2 in each park. In my opinion, the reason for taking the tour is key. If you are taking the tour just to expedite your trip or to access FOL then I think it is not worth the extra $. Sept. is a slower time of year and you will not have difficulty managing your time or have long waits in the lines. However, if you are taking the tour to have more of an insight into the parks, then, by all means take the tour. They are so knowledgeable, personable, accomodating and make the tour quite interesting and fun for adults and kids. They take a personal interest in each member on the tour and you will feel it was worth it should this be your main reason for taking the tour.
Good Luck in deciding!