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