OK... the deed is done. I finally got the low voltages guys to come back and run the height speakers. $609 worth of labor, it was not easy (and I had already done the wall part up through the fireblock).
But the sound is a very, very impressive upgrade with suitable movies. I went back to Stranger Things 1/1 and played the opening and... it sounded the same. Then I looked and no atmos in it. (Accidental) sanity check good.
Tried a bunch of more recent shows, then some YT demos, and there is a huge difference in the "surround" nature of it from the heights. Far more than I expected, even when it's fairly subtle, not a jet going over even.
Very worth it.
A royal pain in this house to install. I learned something. I was going to cut the ceiling holes and have it ready but I couldn't find the studs. Stud finder (expensive one even), tapping with a small hammer. Nothing. Long story short -- there are THREE layers of sheet rock, including two old layers that are really hard. We ended up finding the studs with a 1" hole and bent wire. Placing the speakers was not perfect, I'm maybe 6" off symmetric to miss the ceiling joists. And a wonderful time to use my laser level that mostly sits in the toolbox.
The helper of the team tried cutting the holes with a hand saw - about 10 minutes later (and maybe 3" of cut) I talked him into using my sabre saw. That went better, but here's the blade after the first hole, so several blades (he didn't even realize why it got so slow). I didn't have any really hard blades except very tiny tooth metal, so just sacrificed a few wood blades.
Got REALLY lucky on the KEF speakers. They open to about 1.6" or so, the sheet rock and dynabox box were right about 1.55", just barely, barely fit.
I'm not sure if the dynabox boxes are a good thing or not. They were easy to use, but with all the acoustic foam they send for the inside there's very little air space in those boxes. And they were very expensive. But so far they sound really good. Have done the Dirac Live thing, but no measurements afterwards.
But overall absolutely worth it despite the astronomical cost just for those two additional speakers, in terms of improving the overall setup.
Would have been much more worth it with a house I could more easily run wire to myself, but that's not the HT's fault.
Oh... while everything was out of the way, replaced the 8 year old LG 65" with a new LG 77". A foot does make quite a difference. I am a bit surprise there was not more difference in the picture though (other than size). I guess that speaks for how well those LG OLED's hold up. But my son happily adopted the old 65", so it's not wasted, and they were almost half price for the superbowl.
And kudos to Costco. It was $2300 when I ordered, then dropped to $2000. One 5min max phone call got my $300 refunded. Good folks. Plus a free 5 year warranty.