I've only witnessed moshing once at a DT show at Toad's Place in New Haven. For the most part, the crowd is very similar to a Vai or Satch show. Calm as a whole, but there are always a few nuts who try too agressively to press up close to the stage. Avoid the front couple of rows and it should be cool.
I think DT have some of the best fans (loyalty-wise) and some of the worst fans (being rude to the opening act). I would never, ever want to be an opening act for them, LOL. I guess that's the unfortunate case for lots of opening acts, but it just seems to be a degree harsher at DT shows.
paul