Thanks for the comments and feedback, guys!
Here's WiP pictures of the second half of the Havoc squad, including the champion.
Champion. As I'm going for a thoroughly corrupted Night Lords force, I thought it'd be cool to have this guy have a corrupted backbpack from the possessed kit. I also gave him a small helmet plume, to signify his veteran status among his brothers.

Battle Brother

Weapon Specialist

Battle Brother

Weapon Specialist

I hope you like them! All C&C much appreciated.
Replies!
@ Race Bannon: A bit of Heresy once in a while never hurt anyone. 
@ Barrabas Sogalon: Hey buddy! Long time no see around these parts!
THanks for the comment, and yeah, the brutal Chaos Helmets do combine well with MkIII, eh?
@ Mechanist: No MkIII helmets in the second squad, unfrotunately - I'm a stickler for consistency... 
@ Uveron: Hmmm I looked and can't see anything wrong - it's just the way they mesh together. Might be an odd camera angle? About the painting: I know right? With dedication you can make it work.
@ Teetengee: You're totally right. In fact, the way I wrote about the Salvo rule was a regurgitation of the interpretation of a buddy, who was building a nasty list. Now that you've made me realize salvo actually prevents charging, this gives me ammo to nag him

@ Trysanna: The skinning pits are where I lay my head. Of wait, that came out wrong.
I'm thankful for the offer, but am afraid they're promised to someone else...
@ Viridia: Underslung is so awesome! It's not just the MkIII - but I appreciate the sentiment!