After working up better textures, I revisited my initial instinct to simplify by offering a more limited array of objects, but leaving it up to the user to copy/paste lighter/darker versions into the active folder.
I've decided to not burden anyone with that nonsense. Instead, I will now have ALL versions as discrete objects always available. This means light and dark flavors of green, yellow, brown and straw, in the 2m and 1m heights, and in the 40m and 10m wide sizes. That's 32 objects in all.
An additional benefit is the option to mix slightly different colors for a more variegated field of grass.
I'm sorry for putting everyone through this ongoing, evolutionary process. I really should take my time and let new projects settle for a while as I keep tweaking, before rushing something out.