Let me start this off by saying I've ran and been around many of the forum boners. I've had DC subs in my car for the last 3 years and they have always impressed me but I always felt they where missing something. They wanted more power but that's not efficient is it? Ok on to the comparo
I've had the XLs in many boxes so I'm going to go off the one that was simular to the box I have the DDs in. 3 cubes net tuned at 32 for the pair. DC recommended size vs 4 cubes net tuned at 33.5 for the DDs. Both running off a DC 5.0k. The DCs had voltage of 13.6 from a 200 amp alt the DDs have voltage 14.6 from a 300 amp alt. The DCs wired at 1 ohm the DDs wired at .7.
I've always felt the DD/AQ subs had a hollow empty sound. Not the new i series. They are way stronger and fuller on the low end the the DCs. I'm not sure about numbers but they are peaking way lower pre breakin and sound much louder to the ear AND seem to be wreaking my car more, car has many layers of deadener and was built to not flex.. It's flexing like I've done nothing to it. I could do little shirt tricks with the DCs. The DDs will do hair tricks and move some with the door wide open. I don't plan on metering it cause I don't care about numbers anymore so I can't say what's better but the DDs are peaking WAY lower.
Power handling.. I only have about a hours play time on the DDs, they are seeing more power then the XLs but seem to be taking it better to this point. It's not that much more power.
Conclusion.... I can see why DD stays on top. Theses subs are pure hammers, sound amazing with little breakin. Everybody talks about the cost of DD. it's not anymore then every other big sub. I was looking at Mayhems, PSI platform 3s, and the 9500s. All where very close in price. I think I made the right choice. I'm officially a DD nutthugger. I'm sure ill be even more pleased with the M4a.