I talked to the guys at RE the other night, and brought up the idea of buying either an SX, XXX oldschool or the new XXX.
he said that, under no circumstances should I get the XXX if I was interested in DDing at all... that it was just "way more sub than a daily driver would ever need"
He did, however, refer me to the MX line that is very new. It's rated at 1500 rms and is a nice compromise between the SX line and the new XXX line.
If you're really interested in something more powerful than the SX, but you still want HQ, you might want to look into the MX series.