Mathias, you are paranoid. But I like it when you guys disagree. It's turning into a trademark of sorts. Err. No, my wording is craps
Dusty, a way to blend between rock colors might be to dither slightly. I know that your current style is very non-dithery, but dithering between colors of the same value and saturation but different hue might give satisfying results.
Man, I love extremely-low-contrast dithering * 3 *