What do inwalls sound like?

I just purchased a pair of niles MP650 inwalls for rear surrounds,I have been using B&W LM1s on stands and they sound great.I realized I can get wires to the rear wall through the attic and kitchen cabinets so I got the idea of inwalls but now Im hesitating to cut hole in the wall because I dont want to go through all that trouble and have them possibly not sound as good as the LM1 which I could just mount on the wall with MUCH less work.Please give feedback with experience with inwalls for rear surrounds,thanks.
Check Floyd Toole's discussion of this in his book 'Sound RFeproduction'. Floyd can orient you to what to expect.
I've been installing inwalls for a while now, and I have wowed so many people. It's quite funny, becuse they can not see were the sound is coming from. Now a pointer, to get the best sound read the specs and see how much air space you will need. I have found that some spray foam to seal a chamber ( yes everyone it dose work and sounds very very good lol ) best of luck and you won't be disapointed