I gotta pipe up...
With regards to ride quality:
As mentioned above, tire pressure has a very significant effect as does tire construction. As these are spring/mass/damper systems, changing one of the three affects the other two.
So, if you drive around with your tires at or near max pressure, that increases the spring rate (the tires are a spring in series with the vehicle springs). So, the damping rate (all that the shocks do) must be adjusted accordingly.
Also, if your truck is heavily loaded, it rides smoother. Another change to the system!!!
IF you compare similar trucks (same wheelbase, spring rate, same tires, same tire size, same inflation pressure, 4x4, etc) you will have a fair side by side comparison for shocks.
THAT IS THE ONLY WAY TO COMPARE!!!!!
With regards to gas charged shocks:
The gas pressure is used to apply pressure to the oil to keep it from airating
in all charged shocks. The higher the pressure (to a point), the better it works.
Tube size does matter! All other things being equal, a larger tube will hold more oil and have a larger surface area to disipate heat. But if this is a consideration, you need a better shock than the production stuff mentioned here. And a larger tube has higher torsion and bending stiffness than a smaller one.
Rod size matters too! Too small a rod diameter will bend instead of forcing a piston through the oil. Again, if this happend to you on your Ram, you are probably doing something wrong and/or you broke a bunch of other parts.
With regards to shock selection:
I have the Rancho 9000's with remote. I installed them about 2 months before the IAS shocks came out. At that time, the only shocks I could find were the same fit for 1/2 tons. Since I knew that I wouldn't be satisfied with a "one size fits all" damping setting, and since I would have varying loads on the truck, I installed the only manually adjustable shock availble. If Bilstiens or Konis were adjustable I would have installed them.
The Rancho's do what I expected over the correct range of adjustment
AS LONG AS THE TIRE PRESSURE IS CORRECT. However, if you install a larger tire on a dually, you can't lower the rear tire pressure to the recommended pressure to regain ride quality because the tires will rub.

(I'm buying 215's next time). If I had it to do over again, I would consider the Edelbrocks, depending on the warrantee.
One note about the 9000s: If you live in the rust belt (AKA salt belt), install the remote kit or you will loose the adjustability feature. Rancho used a POS sealing method to keep moisture out of the adjustment area and the adjustment pins will sieze, I replaced 2 of mine at 1 year.
Sorry for the book, at least you didn't have to take the class.
