I would say no, you don't need to neck rein, because I've seen way too many experienced endurance riders using an S-hack and direct reining.
Of course, they're also riding on a trail, so the horse doesn't need a whole lot of correction, either.
I wouldn't ride with constant contact - just let your horse move out on the trails with a loose rein and then cue him when you need to.
Drambuie really didn't respond to the hack from the ground at all. He is a bit hard-headed so I am not surprised! He is too aware of other horses and a bit herd-bound, so I may have some trouble with him! With all the other issues I have been having with that horse it is not a big concern right now...