66 DC is working regularly actually. Humans, Shadar-kai, archers, casters, they all get easily assassinated with that DC. Berserkers and Giants won't even be assassinated with 70 IMHO but haven't really tried. DPS would not be pitiful. It will still have Improved Sneak Attack, Perfect TWF, Action Surge: DEX and CON, Haste/damage boosts, Agony 15-20/x3. Tons of survavibility with 25% perma dodge, Shadow form, Ghostly, Incorporeal. Over 700 HP taking both toughness and Epic toughness.
Trying to work out my PRR at the moment thou. It's just the base 14 from the Blue slot. Might get the prowess set for another +15.