Rich -
I'd be curious whether the pro shop itself is aware of the pace of play numbers. When I booked a group to play there in fall 2000, I was looking at a particular tee time, and trying to estimate whether our group could make an 8:30 dinner time. I stated that with a 4.5 hour round, we should be able to make it, and the pro shop clerk corrected me and stated that golf at Arcadia Bluffs takes 5.5 hours plus to complete. To me, that was a curious stance for a pro shop to take - talk about setting up self-fulfilling expectations. As far as walkability, it's nice that the course "encourages" it - but I really don't see how it's feasible. There are some green to tee walks that are monsters - 8 to 9, 16 to 17 stand out in my memory.
As far as whether the course is manufactured - the contours may be natural, but they did remove a great deal of the trees on the course (which probably contributed to the course's environmental problems). In my view, they went overboard in opening up views of Lake Michigan from everywhere on the course. I think they could have left a number of trees on the course, and created areas where views were "punched through" the trees with greater dramatic effect.
As far as the "dunes" nature of the course - it is not on a dunes, it is technically on a bluff (hence the name of the course). The area I took Dick to visit near Point Betsie really is a dune. There is a difference - in dunes areas more hills and valleys are created by blowing sand collecting in areas. Unfortunately (for golfers), golf course construction is not possible in a true dunes area in Michigan. Fortunately (for golfers) golf at a place like Arcadia Bluffs - on a 150 foot bluff overlooking Lake Michigan - is possible.