By the time I finished writing my second post on this, I had come to agreement with you. The room effects cancellation advantage of a four sub system can be adversely affected if they aren't playing the same signal. And I think having that free room fix may be the most important thing I can get from the 4 subs.
But James your point relates to the initial reason I asked this and I read something from JL Audio about this exact concept https://jlaudio.zendesk.com/hc/en-us/articles/205061040-Adding-a-Home-Audio-Subwoofer
The advantage I have is the Trinnov pre/processor lets me have a couple dozen presets and all the routing for channels is done electronically. Then it builds a custom filter for phase, amplitude =, delay etc to fix as many anomalies as possible before sending signals to all the amps.
So I can have one set up where all the bass management & LFE goes to all four and they do their axial mode cancellation. The Trinnov images each speaker in space using a 3-d mic so it will know there are 4 subs in a 1/4 config and apply DSP accordingly.
But I can also do a second preset and route the LRC, LS, LRS to the left subs and the right side channels to the right sub for music recorded using actual stereo imaging and mic techniques. This is even valid for surround recordings because if they do a live room right they will have a mic corresponding to each speaker and so the mix will reflect essentially a stereo image left and right to the ears, just with the multiple speakers on the left & right sides respectively as arrays, essentially as a single speaker system just not in the same box. But designed to reproduce all the audio info coming from that side of the room .
Anyhow thanks to all for helping me think this through. I will advise as to its effectiveness once its operational