I love the political correctness of that Scout Squad. +rep for not being a racist.
I've honestly never seen any black/brown Space Marines, and that makes me sad. Flipping through the codex, they're all white dudes. And I've done some research, and I understand that one of their special implants allows them to alter their skin tone to fight off radiation, but still, I thought my Marines should be a group that is selected from a world that is as diverse as our own. (Still don't know what this chapter will be called, or what their background will be, however.) Plus, it did give me the opportunity to try out different skin tones rather than just paint them all Elf Flesh and be done with it.
Oh, and one thing. on the scouts you may want to pay attention to the pouches on the carapace armor. you painted them blue. also, the body of the chainswords may look better if you left them black and painted the teeth boltgun metal. it's a pain to paint so many different colors at times, but it's best to pay attention to smaller details.
For the chainswords, I wanted the swords/weapons of squad leaders (like the Scout Sergeant) to stand out a bit. So he gets a weapon that looks a little bit more like it belongs in the hands of a leader. When it comes to others, I do the weapons a little more "basic" if you will. For example, when I move on to the Assault Squad, they all have chainswords, and will likely be painted black/boltgun as you've described. I just wanted to add a little something extra to those in a position of leadership.
For the pouches, I liked the blue for more of a "uniform" look. (See what I did there?
) I did paint the sidearm holsters to look leather, so they do stand out a bit. But the other pouches I wanted to match the upper armor.