subwoofers and panels don't mix

Mrtennis...I designed my custom sw systems so that each of three Maggie MG1.6 has two big sw drivers mounted in the wall behind it. Large cone area (small excursion) and location directly behind the panel ("plays through" the screens) works for me.

Gregm...My three SW systems are "sealed enclosure" which as you probably know is not the same thing as "infinite baffle". The enclosures (which are all the world like coffins standing on end) are embedded in a wall. Their front baffles, which go floor to ceiling, are covered with acoustic foam (for the Maggie backwave). Fabric goes over the whole thing, so the SW systems are completely camouflaged.
Phasing is easily verified using my spectrum analyzer. (Out of phase produces a deep sharp notch at X/O).

Mrtennis...One characteristic of my system which suggests that the SW and Maggies are well integrated is that, while playing a pink noise test signal I can sweep the X/O frequency between 40 Hz to about 300 Hz without any change in the sound. When playing certain kinds of music, loud organ and the like, I push the X/O up to 300 Hz or so to get that "slam" which Maggies lack. Chamber music is down to 50 Hz. Most of the time I am at 80-100 Hz.

"crossed over at 35Hz" !!

IMHO, a subwoofer that can't go higher than that, unloading the main speakers, is just as bad as one that can't go lower than 35 Hz. Sometimes audiophiles seem to get into a contest as to whose SW is crossed over lower. It reminds me of a Hoot Owl that lived at the nearby Audibon park. It would hoot back at you IF you hooted at a lower pitch. The hoot would go back and forth until the bird was as low as it could go.