Agree with Danny -- no need to use the MiniDSP. The A370 amps have a nice PEQ on there as well as continuously adjustable phase (delay). There is a lot you can do with delay, XO frequency, the PEQ and amplitude. The whole point of Swarm'ing your subs is to reduce the spatial variance across the listening space while getting close to some target function for the mean response. If you are doing it right, you don't need a lot of extra EQ.
I have a pair of dual 12s on my Vs as my main speakers and plan on adding a sealed set of 12s directly behind my MLP. In my room I don't have as much room as I'd like from the back wall, so hopefully adding these subs will help "remove the back wall a little bit more" and help smooth out some of the issues I still have in the midbass region.
I can get pretty good results just with the two main subs though and large bass traps in every corner of my room. You can get pretty far with 4 12s, and the single PEQ on the A370 (which I use to knock down a peak ~ 40 Hz).