|Paladin of Baha-who?|
Well RoE and ED are not negative energy damage. They are negative energy, but not NED..
And no the reason we are going this route is Dhampire's favored class bonus with Sorcerer is +1/2 points of damage for spells that cause NED. So far, only chill touch does that.
And undead/sanguine sorcerers get chill touch as a bonus spell at level 3. Don't fail your will save though. XD