My apologies, I didn't make myself clear.
The suggestion was regarding the existence or non-existence of the undead CR-special rule in the Dark Omen racial specific skeleton flag, not about balance issues or generalship.
If the theory about the skeleton flag is correct, then wouldn't the unit without this flag last longer?
All units are fearless, unbreakable and have the same stats, but if the Skeleton flag works the way we think it does, it would be obvious.
/Mr Shadow