CCD shocks are about $700 per corner to replace right now. No idea yet how long they last.
The CCD setup makes a HUGE difference in ride smoothness. Coming from a Lincoln Town Car, I was hesitant to get into a truck at all but I chose the Expedition for its ride quality. The CCD option makes for just about the smoothest and most "plush" ride experience you can get in a vehicle like this.
As has been stated, when comparing to F-150 remember the pickup has a solid rear axle and rear leaf springs and those tend to be stiff. The Expedition has 4-wheel independent suspension with coils in the rear.
Also, the EL/Max models have a longer wheelbase and that gives you an even smoother ride. But, Ford chose to package the CCD with huge 22-inch wheels. The shorter sidewall height on those will help you feel the little bumps more. Yes, it's true that the rubber compound and quality will also make a big difference in ride smoothness.
So, if, like me, you want the smoothest possible ride, choose a MAX with CCD then put 18-inch or 20-inch wheels on it and buy the smoothest riding tires you can get your hands on.