Judging by the reviews I’m sure the Kodiak is a great tent, but I’m always gonna vote for the Davis if possible. Made in USA. I have a 12x14 Davis that I use and it’s awesome with a wood stove. Really is a hotel room in the mountains.
I have no experience with the internal frame, but I got the traditional frame and honestly I can set it up solo in 20 minutes. As far as heat retention, the lowest I’ve had it is in the 20s and not stoking the stove overnight there was a considerable difference between the outside and inside. First morning in those temps I woke up thinking “it’s chilly in here the stove definitely went out”. I walked out to water a tree and my thought immediately changed to “wow it was pretty damn warm in there”.
I realize OP has already made his decision, this is really for anyone glossing over the same decision.
Also, I considered the nu-way stove for sometime but ended up with a traditional wood stove. In cold temps propane will freeze up and leave you heatless. I always buy up some Idaho energy logs - they burn for 5 hours or so and burn hot as hell. I’m usually out of camp for the day only returning in the evening... and if you’re considering bringing fuel(propane) with you anyway, what’s the difference between that and a few energy logs for each evening?