colors - especially the tans - are very hard to compare online. We have a dedicated studio and spend an enormous amount of time getting our Kelvin lighting specs correct, and then post-production white balance to work with shadows and the same, which makes tans unbelievably hard to render.
We see manufacturers who cannot get it right. Badger and Geissele mounts, for example, are often shown as this orange-beige color, when the true color is really a golden sand-tan.
We stock B5 and Magpul dealer and also have a Cerakote facility. I would put it this way: B5 Coyote is clearly a shade of brown, and darker than FDE. Magpul is more of a mud color.
Other than that, I would say, don't sweat the small stuff. Ten years ago, everyone wanted the entire gun and furniture to match. With the Scar and Knights M110, HK 416, et. al., having parts with different colors is actually more desirable. Good to have furniture that matches. B5 is a solid company, and I would endorse any and all of their products.