If you mean dh as in racing. The bikes you are looking at are fr. This doesn't change much but it does make a difference in geometry. DH bikes are slacker, usually a longer wb and a long chainstay. Demo (either of them) are meant for hucking and fr. Great bikes but not for traditional type dh racing. (faith is in the same category)

The norco dh is at least the right geometry and setup to ride like a dh bike.

IF you are lookign for a bik that will survive dh runs but you aren't racing, then any bikes mentioned will be fine as that depends on you and how you want to ride.