For weissbiers I like to mash-in at 105°, raise that to 135°F, then raise that to 155°F, then lauter/sparge.
90% of the time I will do that as a step mash, but once in a while I will do a double decoction. For a dunkelweizen with Munich, I would go ahead and go with decoctions. I think they are more worthwhile for a wheat and munich malt beer, as opposed to a pilsner.