if the dh isn't going to be super rocky and knarly I would ride a single crown. Especialy if you want to use that bike to jump and freeride. Single crown forks can stand up to pretty much everything these days.
I always go for single crowns. They feel better on the corners (prob just a mental thing) and they can stand up to just about as much as a dual crown, that said you do get the advantage of tuning your headangle with the dual crowns.