The extra dark green of the swamps is applied to plants reguardless of the tintindex setting. This really decreases the usefulness of Tintindex if it only turns off the biome coloring of most biomes.

For instance the screenshot attaches shows my Lithos:Christmas pack, which attempts to make all biomes look wintery. I've set Tintindex to "0" for the tall grass model. On the left you see it work as expected. On the right swamp coloring is applied to the tall grass anyway, ruining the effect.