I was just reading the thresd discussing the Untouchable rules, and this thought occurred to me.
As untouchables are basically holes in the warp and cannot be affected by psychic powers/warp, what do people think about untouchables and daemonic pacts?
As far as I know untouchables are as prone to avarice, ambition and dark desires as anyone else. However, their nullification of warp powers would lead me to the conclusion that even if one did bargain with a daemon, he wouldn't be able to make pacts for any of the swiffy supernatural twists common such exchanges and instead would be limited to kind of quid pro quo service for service type stuff. (I do task A for you, you go kill Bob in accounting for me.)
After all it's kind of hard to sell you soul when you don't have one...