Axiom claims the in-wall speakers are pretty close in performance to their out-wall brothers, however, the main difference would be that you can't adjust for placement and toe-in issues to find the best soundstage in YOUR room. Placement is key. For in-wall, I would test them out of the wall, maybe on step ladders or something to get an idea what they will sound like.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85