Given that the rule systems are slightly different between Black Crusade and DeathWatch. But I love the Astartes, especially some of those that are either just Renegade or that have fallen to Chaos. Anyway, one of the NPCs in the Black Crusade game that is soon to start I made a Night Lord NPC and gave him the Mk VIII armor (a fitting match ). Will using the rules from the armor history and the different marks negatively impact a Black Crusade game? I ask only because I love the traditions of shown in DeathWatch.

In some ways. Power armor can have all sorts of odd upgrades and such, because if the upgrades are all equal, than everyone can enjoy them. This isn;t so true in BC, as not everyone is a CSM or has power armor. I'd be more careful with PA upgrades as a result. This isn't to say it couldn't work though.

I'd be a little surprised by a CSM with Errant armor though, as its not exactly common in the ranks of the better equipped Loyalists.

He was my old PC from one of the very games I ever played in. They raided a Mechanicum supply convoy going to relieve the Astartes stuck planet side while fighting the Lost and the Damned back upon Red Corsairs. They were able to steal a lot of equipment and luckily I was able to get the better roll and got the full suit of Knight Errant armor. So now its all painted in Midnight Clad.

In my game I really only have one Astartes PC, a former White Scars Librarian that left the Imperium to pursue his own vices. So I think I may end up making anyone who gets power armor able to customize it in such a way.