Knowing full sell he does not have DA's, this needs said. Compression damping is NOT spring rate, that's not it's use, and it's not meant to keep a car from bottoming. Springs support the car, compression damps unsprung weight, the car coming crashing down to the stops is sprung weight moving.
How do you adjust rebound? Easy, you set it where the car feels the best for you.... The more rebound you run, the quicker the car reacts at that end, the quicker it'll take a set, and generally the firmer it'll ride. The less damping the slower the response, the slower the car will settle down and take a set, and the faster it'll generate roll. If you can't tell what the car is doing and/or what changes the shocks make you are either misinterpreting what's happening dynamically, or not changing the damping enough.
There is no litmus test about what's right and what's wrong. Having adjustables gives you options, options that you simply do not have with non-adjustables. If you don't understand I'd say it's in part because of many of falicies you read on the web no matter how well intended. It's ironic that some folks are so hell bent on changes when they have a car full of other changes. I guess they just don't like having changes they can then use to fix a mistake. Is being blindly faithful to an idea better than learning how to do some tuning? And even if you don't use the adjustment, you have a defacto non-adjustable. In the case of Koni vs. Bilstein for similar price but with Koni's better warranty service (most of the time).
7x SCCA National Champion + 7x SCCA ProSolo Class Champion, 2009 SCCA ProSolo Overall Champion
I drive them, I compete in them, I sell more variety of brands than any other company.