Tom454,
You make a good point about adjusting the lifters without oil; I have to admit I was not thinking about it that way. However, my point is that if people realize that the lifter has a certain range of motion, and that's what you're adjusting, they can find a way to adjust the lifters correctly.

It's not as important to ensure that the return springs are as consistent as say the valve spring, because it has a simple job. The return spring's job is to help create a pressure differential between the high pressure chamber of the lifter and the reservoir. The more important spring, is the tiny spring that serves to hold the check ball in place. This spring determines exactly when the check ball opens, and the lifter starts to compensate.

Also, I have to say that hydraulic lifters are the best choice for the majority of people. I say this because as you can see by this thread, it's not clearly understood what you are doing by setting lash. Please, realize that this majority is made up of the people that don't rev their engine to 8000rpm, and they're not trying to twist every last HP out of the engine. There is no doubt that a solid lifter will make more HP, and survive more RPM, that's physics. But, for all purpose use, you can't beat a hydraulic lifter.