I have both styles of Nate's bows and love them both. Both are smooth, fast, and accurate.
The main difference between them is very basic. The Expedition (R/D) is a bit faster due to the design. The D-Bows are more forgiving and quiet. Decide which is more important to you and go with it. Either way, it won't likely be your last BamaBow.
Nick, I also noticed how tolerant Nate's D-Bows are of spine and arrow weight. I can shoot my Thunder Storm 3050's with a 200 or 250 grain head and they hit the same, and not all that different in speed either. I couldn't believe it at first, but it's just another bonus to Nate's bows.