I checked with the peeps at MORE about what to expect on those trails.

They said that trail-wise, Black Hills is just a step up technically from places like Schaeffer. The hills are a little bigger and the trails a little rockier, but at the same time there are far fewer log piles (if any), so a "beginner" can be a lot less intimidated. (Also, less traffic and not all the hammerheads.) You are never far from a bailout point onto pavement. They said it is easier on a beginner than Schaeffer, but like any mtb ride, depends on your sense of adventure and attitude.

Summary: more beginner friendly for technical skills, but can be more demanding fitness/cardio (than Schaeffer).
Also...they all recommended a mtb, vs. a hybrid/comfort bike.