Something really neat happens with inwall speakers. The whole wall starts to resonate. If all your speakers are inwall then great but if you have a beefy front array, which you do, then the sound may present differently from rears and sides to the front. In fact it will. Especially if your walls and the stud bays that you locate the speakers in are not identical.

I have the 422's as my rears in a 5.1 set up and they work great. Considering the size of your drivers across your array I would go with the dipole 534SS. I've installed a few theaters and had very favorable results with a dipole side and rear combination in a 7.1 configuration. That way you get the timbre matching with the fronts, dont have the 4 inch rears, and have a more realistic acoustic presentation. Dipoles do a better job with transient and panning sounds that move through the room than singe axis speakers would do.

Daryl 

Thuanvo,

I have the 534-SS’s as side surrounds and would highly recommend them. The 534-SS’s blend well with wall mounting and I think they would also work well for rear surround.

The sound effects you can get with the 534’s and their Bi/Dipole switching provide a lot of adjustment at the speaker and the AVR to customize the sound.

I am not a big fan in any way of In-Wall or In-Ceiling speakers for reasons that Daryl sited and the fact that once they are installed, there is no room for experimentation in positioning unless you are happy with cutting a new hole and patching the previous.

Like Daryl, I also have the 422’s as rear surround but in a 7.1 setup and they work well in various sound fields.