Gentlemen,
Midvalves and basevalve relationship is like the relationship of the shock piston and the compression adjuster. The Dynamic that ensues is quite interesting. If you where to build a fork or shock on a dyno and create some tests you can map out the relative areas where each valve and combo exerts influence on the total system. I have done this and its quite a cool little demonstration.
The midvalve + basevalve = Overall damping coefficient.
So to prove that build a midvalve with no shims only one very soft check valve, you get the front part graph and not much else through the middle and then if you can push it fast enough you get an interestingly steep tail.
To test the base-valve do the same only no basevalve shims, although you do have to pressurize the system somewhat. You get the midsection of the graph. If you place the top graphs on top of each other the sum is the overall coefficient. Of course through tuning you can overlap on region to another like Marcus points out, and interestingly this is where piston design really becomes apparent.
In the midvalve for instance if you have smaller areas of the piston then the less effective your Midvale becomes as it produces more fluid pressure, and larger deflections making the shims less able to control the area of the valve. The greater the area the less float you can run. I've found that on a wagon wheel midvalve of the WP you can easily run .2 float, yet by way of comparison, on the Showa with less area and smaller volume you can still only run .15 to .2 You would expect with the massive reduction of fluid in the smaller Showa Cartridge you could run almost no float, but it does not work that way do to valve design.. My point is each one of these different designs requires different lifts etc..
If your inclined to make blanket statements the smaller you can make the pivot shim and the lower the lift you can run the better your suspension will work. As your average damping coefficient will be lower and the feel more consistent.