Yeah the lack of C'tan does put you off, but the tomb stalker and sentinel replace the C'tan for the high toughness
MC Niche, and poisoned weapons don't work on them
I have used this list with flayed ones as troops to some effect, they are still susceptible to sweeping advance, as most things get to hit you first. The other good part of this list is the lord Kutlahk, He is fearless
20 blob of flayed ones that are fearless, or a 20 blob of warriors, with a lord with res orb, fearless and can charge after shooting their rapid fire weapons, its gooooooooooood.