I used DU to book our first cruise upcoming in May and can't recommend them enough.
Their response time was very quick. I also contacted Small World, and while they were nice, the responses weren't as speedy or as helpful. Beth (mentioned above too) was extremely helpful in booking the exact room I wanted and even called tech support a couple times for me when I was having issues adding the reservation to my Disney account.
You also can't go wrong getting the best price + OBC. I say go for it!