I'd have to disagree with Pgolde...the Tuba 24 can be used for Dance music. BUT...to get the sound that efreak wants...he may need to stick with Double 18" cabs.
It sounds like he likes the "punchy" sound that all reflex loaded drivers produce due to their abundance of midbass hamonics.
I personally have Mixed two different types of subs together in my DJ/Dance system, one quasi-reflex cab and one horn loaded cab per side.
It was difficult to do, and requires a digital processing crossover/speaker management system (i own a Rane RPM26z)
BUT it gives me the combination of low freqency extension and "punch" that i've always wanted, with boxes that one person can load alone.
The cabs are the yorkville ls608s and the tuba24, by the way.