I will try and deal with the issues as best I can one at a time.
First off I have three systems. The theater is 7.2.4 effectively. There is not sub as generally understood, however the sub output and the LFE is fed to the four 10"drivers in the large lines in the main speakers, so to all intense and purposes they act as subs. In addition the upper two 10" drivers are fed an active baffle step compensation signal to off load the mids. This signal is variable and can be set by instrumentation and confirmed by ear. This is a critical part of the voicing of the speakers to the room.
The center also has variable BSC and is also voiced to the room. The surrounds have a the ability to adjust BSC, but not continuously variable. The rear backs are actively bi-amped, because of the frequency of the crossover, this gives major control of BSC, in addition these speakers are essentially full range with good output to 20 Hz.
I mention this as this probably helps to get even bass coverage. The ceiling speakers have no adjustment except for volume. They have a good FR profile. All of the other 7 speakers, are powerful with excellent frequency responses and all driven by more than adequate power. Total system power is 3,100 watts.
The other issue is that all speakers are far enough apart not to interfere with each other. In my former room, which was smaller there was some interspeaker interaction in the front three, and surrounds and rear backs. Speakers preferably need at least six feet spacing and preferably 7 to 8 feet spacing. In a lot of rooms this is hard to achieve with the front three, and part of the endless center channel problems. The center speaker is designed to have optimal dispersion and coverage to the seating area and cone off from the mains to minimize this problem. This is an issue we don't talk about enough, but an issue I have found to be important.
So this is the curve of the MLP, all speakers except the ceiling speakers driven.
The impulse response from all the speakers is arriving at the MLP at the same time. Obviously this can occur at only one point in the room. Subjectively the system sounds well balanced. The HF falls of a little at the MLP and the other seats as it should as the proportion of reflected sounds increases. There is a slight rise from 30 to 20 Hz, probably from the effect of the back wall. This is in no way unpleasant. There is not a trace of boom.
Now I find on this rig that I use the new Dolby upmixer the vast majority of the time, but do some 2 channel listening and just the center for mono sources.
Most of my sources are two channel with the up mixer engaged. Obviously I have multichannel discs, and there are streamed multichannel sources and cable TV.
I find the new up mixer incredibly good and do not use center spread. The reproduction is amazingly realistic.
The family room is two channel and a couple of subs. It is a system I really like. The speakers are marginally close, and the system does not require a center which would probably be a detriment. I like this system enough I have started the design of a new sub, to replace the current two, which are showing their age.
The in wall system in our main living area is 3.1. I only have the center engaged for true discrete multichannel sources like Dolby digital. The center gives marginal improvement for speech, and I stress marginal. I guess I wanted to design a three way center. However truthfully its benefit is marginal. For two channel sources I do not use the upmixer because of the proximity of the three speakers.
As far as auto correction is concerned all systems have Marantz pre/pros. Only the theater has the latest version.
However, engaging Audyssey really spoils all three systems. For one thing it adversely affects signal to noise. All three systems are inherently very quiet. Engaging Audyssey results in audible hiss at all listening positions. In addition nothings sounds right. Audyssey uses FIR filters, which are not linear phase. I have reason to suspect a lot of the deleterious effects of Audyssey is that is mucking up the careful time alignments inherent in the design of the speakers. Also the room responses are downgraded by Audyssey.
Dirac I have no experience of, however Dirac uses IIR filters which have a far superior phase response.
Since I have designed all my speakers, I am able to tweak them as desired.
So I do not like Audyssey at all, and suspect many of you, if not all, would be better off without it.