Since you've got all those tranny mods, especially the flywheel, I wouldn't be surprised if you lost more than just 4-5hp.
I ran my ASP pulley (which is about 1/3 the weight of the DMD) for 40k+ miles, and I installed the DMD last week.
Power loss? Yes, slightly, but the smoothness far outweighs the few hp that I did lose. Actually, the car seems to pull a little better from 6-7k rpm... Maybe since I still have my SHO Shop power steering pulley, the HP loss isn't as great.
Whatever floats your boat!
Oh, and I, too, haven't seen a Duratec blow up BECAUSE of a UDP either, hence why I've had mine on there for that long.
-J
