The history of it all is interesting. The people who kicked off the whole industry were all about crazy fast speeds down fall line fire trails. By the time I personally encountered the sport, the trend at least locally where I live was just to go for a mellow ride in the woods on doubletrack and some singletrack. More recently, so-called flow trails have become increasingly popular, sort of in my mind harkening back to the original idea of blasting downhill and hoping to survive till the end. Flow trail systems are what I see as bringing in the younger crowd, at least locally to where I live.