Point me in the right direction, small, new, energy efficient home

With ICF we go back to propriety materials, requiring a stucco crew/guy with that soft stucco they now use, plastering the interior instead of drywall, and the far more complicated repairs behind the wall or future remodeling.

And for whatever reason stucco isn't very popular in MT, so I would think there wouldn't be many stucco crews/guys around these parts.

And with 10" Rastra blocks (that is the brand I have used) you end up with a finished wall of about 12" and R24, vs my 5" concrete finishing at 12" and an R27.5. Or R30 plus if I can make 4" work.

ICF has some big advantages in construction, if you can assemble Legos you can assemble ICF.
You don't need to know how to weld, fabricate or finish concrete.
You don't need a 12'x12' tilting steel form, I am making it big enough for other projects.
You don't need lifting equipment.
And many of the details are pre designed.
But in my case those aren't obstacles.

I have lifted and moved expensive and fragile lathes, mills, etc,, that weigh 2 tons a few dozen times, what is a cheap 3 ton panel? lol

There are different types of ICF and I have not had a hand in them. But one type is to use insulation panels as formers and pour the concrete between them rather than using the lego blocks.. When it comes down to it we are looking at a lamination of concrete for strength and insulation. You are doing the same thing except you are having the thermal mass on the outside.

http://www.hhcelcon.co.uk/by-product/vertical-elements

Similar sort of thing using AAC.

The finish on the inside or the outside are really just a matter of attachment. I have still to clad my Boiler Building, I went with MgO mainly for abuse resistance, but unlike OSB it is quite happy sitting there. I have some bathrooms to fit out and if I can get hold of some more I will use it as opposed to cement board etc.

If I had used AAC I would have just painted the inside, foamed the outside and then whatever finish,

Probably will use Hardie Panel.

As the Boilers are not operating yet and I also have my water system in there I am heating it with a small electric radiator.