I attended some of the meetings at the Maplewood Library with the South Mountain Conservancy when the proposal was discussed. The JORBA leaders and the Conservancy leaders saw the value in having mountain biking in SoMo, but the membership was a little disgruntled about the idea. They were more concerned about reinstating underbrush and shooting deer than sustainable trails.
You can find the trails that were built by JORBA a while ago are well built and the recent trails built in the Mayapple section were built by bulldozer.