I've been in some of the glades at Nubs, but I'm not much of a tree/glade rider at all. The areas I've been in (between some groomed trails, and you know, that one section off to rider's left) were pretty tame and manicured. There could very well be more serious stuff than what I was in -- I just didn't seek that out. (I've taken my then 5-1/2-year-old son into the marked glades between trails at Nubs. (He also has done a run on their snowcross course with me.))
Sooner or later your legs give way, you hit the ground.