Chuck
I personally believe that the CDR valve is overrated. I have opened one of them up(pics to follow) and there is not much inside. Essentially, the blow-by from the crank/valley/valves is routed via the CDR up into the intake to be reburned. The internal diameter of the opening through the CDR is approximately 3/4". There is no restriction to the flow through the thing, and intake vacuum, although small, is all that is required to maintain "negative" pressure in the crank area.
There is a diaphram, and a soft spring, which holds the diaphram open. It appears in the event of a huge obstruction to the intake, that this diaphram might be able to be sucked shut to prevent the engine from ingesting crank vapours/oil and continue to run itself to death. I hooked a shop vac to the intake side of this unit, and I couldn't get the diaphram to snap shut, so it'd take a huge volume of air to move it.
Any oil that collects in the thing is allowed to drain back down into the valley, but obviously some manages to find it's way into the intake.
There is no service that'll make any difference, nothing will change the oil burning, the CDR itself is in no way responsible. The blow-by is a sign of overall engine condition, and is quite normal in our engines, especially older high mileage ones. You can replace it, but it'll just mean you made a $50 donation to Ford. Won't change how your engine runs at all.
Obviously, this is one of my pet peeves....