Just the general comment that microperf screens do in fact audibly affect the sound. Since the average HT speaker has smoother and wider frequency response than the commercial theater speakers, the differences are sometimes dramatic. I don't know if any digital receivers allow frequency equalization of only the speakers behind the screen and not the others, anyway I've never seen such a feature. Boosting the attenuated frequencies to the front speakers would accentuate the same frequencies in the surround speakers, is my guess.
The audio is very important to me, so the microperf is not a compromise acceptable to me, as I mentioned before the speakers dissappear in a darkened room. Also, I have tried the phantom center channel and it can work very well, but the "sweet spot" got really small in my smaller room, there really was only one seat that got balanced front sound. Of course my screen is only 72" wide and the RF and LF speakers only that distance apart - larger rooms would have larger "sweet spots".
If you (or your spouse) prioritize the benefits of microperf above the audio, you may be able to largely compensate for high frequency screen attenuation by removing the speaker grilles from the speakers behind the screen, and leave them on the surrounds - if you are lucky, the sound may more or less balance out.
Gary