Good points for the
DP:
They can shoot twice. You can use Burning Brand of Skalathrax AND a Witchfire spell in the same turn. A Sorcerer can't do that (though Ahriman can).
DPs attacks are AP2. Put a Black Mace on him and attack at AP2 with it due to the Smash USE (and no, you don't have to "smash" to gain the AP2 benefit).
DP can fly. Wings means he can't be shot except by Skyfire until he's grounded. Provided you place him correctly, he can always fall into cover or out of
LoS. If your opponent is shooting at him, he's not shooting at your Heldrake. Wings means he has better mobility on the ground. A 12" move and then assault, or a 6" move and he can re-roll his Assault distance.
DPs need to be played intelligently, so it comes down to how you use him