But now I found one last problem. When broken, the gear displays the texture "gear" that I made for the particle but it's in red. Look through all the redstone models and there's no tintindex left to remove or overlay.
Unfortunately this is hard-coded by Minecraft. It's one of those little "quirks" that you're just going to have to live with.
I'm not sure how Optifine's method of changing redstone dust color affects redstone dust without a tint, or how it works with the particles. However it's still something worth checking out, even if only in the hope that you won't have to see this while Optifine is installed.