I dunno, are houses really EVER done?

They poured the foundation for mine in 1922, and the house ain't done yet. :-)

A 2-ton minisplit handled 1600 sf admirably. We had 3,4 nights when we had to bundle up, usually after a cloudy spell. I'm still looking forward to hydronic. Ceramic tile over concrete at 70 degrees may not be physically colder than carpet at 70 degrees but it is relentless.

Several of you have mentioned thermal bridging through concrete...I first saw AAC in eastern Europe, where it was being laid up in confined masonry walls for new residences. Riding through the country, I saw many mid-floors being poured by crews of 3 or 4 guys with a portable mixer hauled up to the second floor. I think the bond beam might have simply been the outer edges of the mid-floor. The method depicted in Safecrete and other American install guides (with rebar in grout filled holes) seems like thermal bridging would be reduced...but what do you call this kind of structure? It's not really "confined masonry", right?

And btw, is it feasible to fill the 3" cores and U-blocks by hand if a mixer is available? Might there be a cold joont in the bond ring by the time a small crew get back around to the starting point? If so, how does that compare tp the intentional layering of 3' lifts in an ICF wall?

No problem for 2 people to pour cores and bond beams by hand with a 3 cubic foot mixer. Fill the beams part way and then place the steel. That way you aren't messing with ties or chairs or impeding the flow of concrete down to the bottom. Grab a rebar stick after the core is full and work it up and down until the concrete level doesn't change.

To clarify, the common type of AAC block has a compressive strength of 500 psi, or roughly equivalent to unfilled cmu. The steel and concrete in bond beams and cores are for shear strength. You're not likely to have many earthquakes or hurricanes in Indiana, but it isn't necessarily bad that CMU crushes, absorbing blows, and flexes when the earth shifts below it. It is plenty strong structurally. I have 2,280 pounds of water, in a form of a hot water tank and heat storage tank, hanging from bond beams in my house, and another couple tons of rough cut lumber hanging from bond beams in the garage. (Love those wedge bolts.)

As I pointed out before, the concrete in AAC is under 10 percent of volume and is insulated on either side by what would be effectively 3/4 inch of eps. Thermal bridging isn't great, but it isn't the horror that GBA makes it out to be.

You get more with ICF: more compressive strength, more shear strength, more static R value. You also get higher costs and more serious consequences in DIY mistakes. So the question is what you need. In my small passive solar house, it would take a multiple generations to recover the cost of ICF, and comfort would suffer because exposed AAC buffers heat more effectively. Your results will vary.