We managed to integrate my 2 Velodyne DD-15+ subs as LFE channels with the Titus 8T's running fullrange on the main channels.
These measurements are at the seated position (front row purple, back row blue). No global EQ was used at ALL. Just careful placement and good room integration of high quality gear.
The Front Row:
Ignoring the tangential room mode at 80Hz, the bass response was +- 5dB from 12Hz to 80Hz
The Back Row:
+-6dB from 12Hz to 100Hz
I am sure I can further tune this, but it's sounding so darn good right now, I'm not too inclined to break out my measurement gear again for at least a week or two.
The Velo subs aren't even needed as the Titus bass drivers really fill my room with incredible tactile and linear bass. However, I use them for the LFE channel for multi channel music and movies. I've never had a pair of speakers in my 6,000ft^3 theater room capable of delivering reference level bass response at all seats without the need of powered subs to help them along.