I went with the Curt R16 slider with the E-16 head. I made this choice based on the fact that it has 1-2 inches more travel distance for more clearance at the cab. The side beams are also a lot lower to the rails allowing my toolbox to clear the hitch.
I was told by the installer (highly respected independent RV Tech) that the slide jaw Curt was superior and should experience less "chucking" than the dual jaw Reese Pro Series.