Originally Posted by hamishspence
The Black Crusade game allows you to play both Chaos marines and human heretics- it tones down Marine wargear a little compared to Deathwatch- but it's still better than human wargear. A "Legion bolter" will pack a little more punch than a human bolter, and so forth.
And the armour is still comparable.
The Inquisitor game also has stats for both marines and humans- and Marines are even more durable than in Deathwatch.
The Cain book The Traitor's Hand has the Chaos marines wading through hundreds of humans with minimal damage- and it's just Cain is that good a swordsman (according to Amberley, he's one of the top swordsmen in the whole sector) that he is able to not get killed. Even then, he's either holding it off till Jurgen can shoot it, or stabbing a badly weakened Marine through an existing hole in the armour.
Both of which scenarios are quite believable and even likely
in the various systems. (Damaged armour does get reduced armour value, anything other than medieval weaponry has a reasonable chance of getting through anyway, and certain weapons do penetrate a lot better.)
The Black Crusade does have some small mechanical differences/updates, but the armour and probably weapon differences are actually more intended to be because of the state of the armour used, with few of the systems still working and so on.