I've been reading about those window/wall units. They cost almost double the price of a regular AC unit. And are pretty dang efficient.
But, when the temps get down under 40 degrees, they start loosing efficiency due to defrosting requirements or, they just frost up and stop working.
If I had the voltage wired in, and warm-air duct work,
and the money for a Hallowell system, that would be my choice..
Hallowell International: Acadia Heat Pump
They work pretty well at very cold temps..
http://www.gotohallowell.com/assets/...hrenheitLR.pdf
Maybe next summer I'll see about installing their hotwater HP, if it's ready to ship by then..