Which sub - JL Audio Fathom or Velodyne DD?

I have two Vandersteen V2W subs for LFE, but they are showing their limitations. The V2W worked great in my previous smaller HT room (1400 cu. ft.), but even with two of them, the Vandersteen HT sub can't go low enough or play loud enough without strain in my current 3200+ cu. ft. treated room.

I've been doing some research, and I think I've narrowed down my choices to a pair of JL Audio Fathoms, or a pair of Velodyne Digital Drive subs. The JL Audio subs seem to have more output and perhaps a bit more low freq extension than the Velodynes, but the Velodynes have the digital room correction function. Which is the better route?

Lastly, should I get matching pairs (i.e. a pair of Fathom F113s, or a pair of DD-15s), or is there a benefit to getting a F113/F112 pair, or DD-15/DD-12 pair? On paper there seems to be benefit to mixing like this to get output advantages throughout the typical subwoofer frequency range. Does the theory match up with reality?