Wayne Parham Messages: 18786 Registered: January 2001
Illuminati (33rd Degree)
What you have are distributed multisubs, which will provide extension and modal smoothing below 100Hz. That's a prety good setup, even without flanking subs.
What flanking subs do is to provide smoothing in the 100Hz to 200Hz octave. They work a little bit differently than distributed subs. Both are used for extension and smoothing, but their proximity to the mains puts their smoothing region in a different band.
If I had two dissimilar subs, I'd run them the same as you have.