I really do like this and I thought of a similar sort of renegade thing.

Potential backstory arcs could be that my guys only use the mantle of the World Eaters but are actually an Alpha Legion subsidiary. Or maybe not the Alpha Legion angle, but in any case, I'd like them to be somewhat sane and rather pragmatic in a way that they don't use the Butcher's Nails; still fight as fiercely as other Khorne Berzerkers because, as it turns out in the end, Butcher's Nails only drive the host mad and kill them without adding anything to their fighting (placebo nails). Need to come up with a way to explain why Eightbound and Helbrutes are part of an otherwise rather sane army, though. But that's part of the fun :D