I'm not with DU, but I can tell you that if the cost of using a
travel agent is the same as not using one, then by all means use one! There's no limit to the number of things that can go wrong with a trip, and I'm not just talking about little things like the wrong date/wrong hotel. I'm talking about reservations mysteriously going missing, missed planes, connections that suddenly aren't and so on.
If you book on your own and you have trouble, you have to spend the time and the effort to get it straighted out. If you book with an agent, THEY spend the time and effort on your behalf.
I had a client on a Hawaii cruise that ended up being cancelled partway through. While other passengers were waiting in one of two designated areas to see if their arrangements could be straighted out and taken care of, my client was literally walking along the beach and enjoying an unplanned day in Waikiki. She knew I was taking care of things for her, so no stress for her!
Given the excellent things I've heard about DU, I can't imagine they would be doing any less for their clients.