HI stpierre76, please do let us know what you decide on and how you like it as there are, I think, very few of us that go the in-wall route for upgradeability reasons I suppose. However If you dont mind me asking other than a large soundstage what else are you looking for from the your music (warm, detailed, rich, lean, fun, clean)presentation? The reason I ask is because though Ive not heard any Tannoys am fairly certain they will sound quite different from the Logans you were considering before. Make sure you sort out what you like and dont like as most major speaker brands now offer In-Wall Lines.
Also have you considered slim on walls such as the Dali Ikon on-wall? Anyway Best of luck with your project.