I had a custom Nightshade 18". longer coil, Quad spyders, thicker tensils, etc etc....I loved the shit out of it. Ran a 3000D Sundown on it daily at 0.5ohm, and it took it no problems. I don't know about it comparing to the BTL/DD stuff, but it would hold its own very nicely.
IMHO.....go for a DC Audio LVL 5...and search on here for pics of Andrew2944r username. He's my team mate, uses 3 18" DC LvL 5's and is just plain sick loud on 6 Sundown SAZ 3000's..//content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif