from what I rode out there, grip is not a major concern, it's more the rocky stuff that is the main part of the trails, the surrounding ground is usually quite well packed down and/or covered in leaves etc. depending in time of year. I rode the Wild101 with a 32x16 an I could NOT go any bigger than that, some of the climbs are LONG !!
Perfect bike might be a rigid 29er with a not too aggressive knobby.