Mainly cheap. I don't think they'd have any real special rules except the marine level strength and toughness. It's just a hole I think chaos needs filled because they really just gloss over the procedure.

I suppose you could give them rage and something else to represent their enthusiasm in attempting to curry favour. Even moreso than the space wolves chaos neophytes are going to want to impress as graphically and as spectacularly as possible in order to be seen as 'worthy'. I imagine they'd be put in death pits until only the toughest survive and then implanted with organs and sent into battle ala the blood claws to further weed them out.

I would think that, given the rather blase use of resources on blood claws as well as the effort going into making them, the space wolves are capable of sustaining the high casualty rates the blood claws accrue. Although most chaos legions couldn't sustain as many, I think it goes to show that they could at least have some greater capacity to recruit than we are currently given.

The space marine scout is an odd beast, arguably infiltration requires more skill than other activities so it's odd their newbies are the ones that learn how to do it.

I think a small horde of scout equivalents used as fodder to bulk out the numbers would be an interesting addition to chaos.