Gary,
Look at many other rankings and DN is not on the top 100 or top 200. I have played all of the top 10 courses except the to Southampton courses. I can say I was not impressed with DN. I've played Sage Valley, Shadow Creek, etc and to me DN is a generic Fazio design that he stamps around every resort course. Every Fazio course is the exact same, which if you have not played many Fazio courses you would not know this.
Based on my experience with guys I know who are members have either gotten out or want out. I was not impressed when I've played there with the course or the membership. I'm a member at a top 20-30 (pending on the publication) course. What the club has is a solid membership of guys who enjoy golf, small memebership, are active (I'm active and play in most member events and make the hike), great course. I never got that vibe at DN even when I played in the member guest.
What makes a good course is the membership and the course. A good example is Seminole GC it's a decent course but what makes it great is the membership. Played in two events there and the membership made the club.
Now I do have a good friend who is a member at DN who loves it. He also loves to eat spam and Vienna sausages and watches soap operas haha jk. But for my buddy he loves the course and does not play golf that often and when he does it's a get away.
I also have not moved to Dallas yet. I move in August so can't answer the rest of your questions.