PS. I also have a chance to replace the 224s and 325C with the Atlantic Tech 3200 series, but that just seems like a lateral move.
I auditioned the following on wall speakers side by side (room about 17 L by 14W with a peaked roof about 14 feet high).
1. Atlantic Tech FS3200
2. Boston Acoustic P442
3. Def Tech Mythos 2 and 3 (center)
I'll say that going into this comparison, I am not an audiophile, but I could definitely hear subtle differences - but I might not be using the best/proper terminology in describing these differences for people who are much more experienced than I, so please bear with me : )
I'll also say that I was biased up front in wanting the AT's to win. They were beautifully built, high quality, etc., so based on that I just assumed they were a cut above (so much so that I actually committed and drilled permanent holes in the walls to mount these as I was pretty certain they would be the winner in the end....
The speakers were mounted about 5 inches to each side of the 65" TV and 4 inches above the TV, and they are ever so slightly protruding out further from the wall (maybe 1/2" beyond the face of the TV).
First, none of them had a lot of low end reach. I thought the AT's would have a little more bass response because they were the biggest cabs of the three sets and I liked the idea of not "needing" a sub even though I planned on using one. I have an SVS SB12 NSD by the way which is really great.
If I had to choose, I think the Def Techs had the most bass and were well rounded in sound on their own out of the three speakers, but I think other factors led me to this (explained below). I did no room EQ while testing these, and all speakers were set up and mounted on the wall to compare them directly. But, when the sub was turned on (the single SVS), that is when the magic began.
In short, the AT FS3200 and Def Tech's were pretty close contenders. The BA's were decent, but I could quickly tell the AT's and Def Techs were a cut above, so I didn't spend a lot of time with the BA's.
The Def Techs I thought were the winner because:
1. They were a perfect match (in my room) with the SVS sub. The front of the room became a wall of sound with this pairing, while with the AT's I could hear the sound distinctly coming from the speakers versus the sound from the sub separately. This might have just been fixed with some EQ and crossover adjustment, but I could not deny that the Def Tech's sounded just right without any fiddling (and so it would only get better with fiddling, right? : )
2. The Def Tech's had a more pleasing higher frequency response. The AT's had just a slight harsher sound to my ear, again EQ might have fixed that. Both speakers did sound clear and detailed overall though
3. Stereo Imaging/Sweet Spot. This was the biggest surprise for me. The Def Tech's created such a deep soundstage, I felt that the sound was coming from all around (while I did not have any surround speakers set up). The sweet spot was also very wide. I walked around the room and the sound seemed nearly the same anywhere I stood (within reason), while the AT's were a bit more directional and I could hear the change in sound much more easily walking around the room. This I don't think this could be corrected with room EQ, but maybe this could be fixed by adjusting the speaker placement (wider placement, angling, etc.) possibly? But hands down the Def Tech's provided for me in my room the best image.
So in summary, while I was biased for the AT's the Def Tech's won the day for me.
I probably didn't answer your question, but I didn't hear any negatives from placing my speakers less than 8" from the edges of the TV. I am not sure what the issue is and how the distance of the TV might affect the sound really, so I wasn't necessarily listening for that. The AT's have a "boundary effect" switch that is supposed to reduce the bass peak you get when placing a speaker close to the wall, but I didn't hear a major difference when trying this feature out in my room.
I don't think any of these wall speakers would compare with the bass response from towers, but the SVS sub is so good, and with just one, I was very pleased with the combination of the def techs for the mid/highs and the SVS for the lows.