Your opinion on best In-Wall Speakers for HT Use?

I am building a relatively high end Home Theater system based on a Lexicon MC12B and a Lexicon LX-5, five channel amplifier, for the rear 4 speakers. (FWIW, front amp is a Theta Dreadnaught and front speakers are undecided, but probably Vandersteen)

I am forced to use in-wall speakers (not wall mount, but actual in-wall) for all 4 rear channels, 2 speakers to be placed on side walls and 2 speakers to be mounted to ceiling, obviously firing downward. From your expereince, what are the best in-wall's for my use? I am considering Thiel PowerPoints but at $5,000 for all 4 speakers, that is a bit much but I am open to your ideas and opinions. Thanks in advance for your advice.
I just redid my listening room and in the process choose and installed the B&W Signature 7NT in wall speakers. These replaced the THX certified Fosgates which were physically large cabinets and surface mount.

Over the years I owned or tried side channel versions from Vandersteen, JBL, Chartwell and others. I had hoped the B&W would be "about as good." Considering their handicap of being in wall.

I must admit surprise now that I have run them for about a month. Not only are they delivering powerful dynamics and great tonal balance, they are setting a new level of quality in the high frequency region.

Really a very good little speaker.
If you are investing the kind of money suggested,I would have a look at Legacy's new in wall line up;they have great specs., although I haven't heard them,they warrant investigation for a premium system. I own other Legacy products used in one of my HT rooms,and it is great.