Moving. Take older equipment or not

If we're talking about them making new speakers, I'd have to assume it would be like a light fixture, i.e. you'd have a place to connect power line to wires on the device with those screws. I sure wouldn't want the power to be coming out of the wall (like I have set up currently (forgive the pun) in my kitchen. But yea, doing structured wiring to all those locations would be key.

I was think it could be similar to how my alarm control panel is setup. It's plugged into the socket below where the panel is installed.

Having a junction box (or whatever it's called) sound good, but it's not how speakers are typically installed. I would definitely want it done to that passive speakers could be installed. As well, it sound like you're going to require professional installation for sure now

Well, it's the power that's the issue. I had an electrician install plugs near the ceiling for my Play:1s that are mounted with Flexson speaker mounts, but if I've got an "in-wall" speaker, I sure don't want to have any power plug/line coming out of it and trailing down the wall. So, yea, pretty much professional installation.

I went almost entirely with in-ceiling and loved it, particularly in a room with vaulted ceiling.
While I have no experience of audio with such ceilings, why should a vault make any difference other than for the worse where the sound from ceiling speakers will have to come from further away and be subject to more bouncing around and diffusing before it reaches you? Conventionally mounted speakers, lower in the room and firing horizontally towards your ears would not have this problem; and if that kind of sound projection is more effective in delivering sound quality in a normal listening room compared to ceiling speakers, all the more reason for this to be the case in such rooms.

IMO, ceiling speakers make the most sense in bathrooms, and perhaps in passages if you must have music there. Yes, they are discreet but I would prefer a conventionally placed play 1 unit/1 pair any day for sound quality. And if filling the space is the need, 1 units scattered in different parts of the space, that can still be done without they being visually obtrusive. The other disadvantage of ceiling speakers of course is location inflexibility.

All that said, I agree that Connect Amp still has a role with them, but not as much as it does with external speakers. Everywhere else inside the home, I prefer the play units approach.

My statement wasn't really about audio science, more of personal preference. I'm sure your correct on your analysis. The sound was more than good enough for my tastes. I liked having the speakers out of the way and coming from a different angle than typical. The ceiling went up to 16 ft, but the speakers themselves were actually at around 9 feet. They were neither horizontal or vertical but around 60% angle (front and surrounds, center channel was not).

As far as the bathroom goes, I did have a single stereo ceiling speaker in there and liked it somewhat. I currently have a play1 and like that a bit better, but I also have a relatively dry spot to place it now.