I was actually up at Killington this weekend while the race was going on (I was not racing). They must have been channeling the Allamuchy event because there was some rain (mostly the night before, but some on race day as well). From the looks of the parking lot (and the view from the gondola) it didn't look like there were that many participants. Don't know if the weather or price had anything to do with this.
The trails at Killington are pretty cool - there are a lot of technical rocky/rooty type trails with some "north shore" style bridges thrown in. It was a little wet and slippery for us cross country/all mountain types, but the guys on the 8" travel bikes were eating it up. The only thing that I thought sucked was that it was wet and the trails were getting ripped apart. I know that these trails were primarily built for downhill bikes, but they really needed to be designed a little better to avoid all of the damage they were getting. In dry conditions it would have been 100% better.