You are referring to the true north
I think the True North is a 1.9 cu ft box , Edit: I initially thought not a square firebox but looks to be maybe a 18" x 18" box, PE recommends 16" wood.
Square Firebox means you can load your wood either way N/S or E/W.
The FW 3000 2.9 cuft fire box might work as the most square firebox design but your wood needs to be cut 17" or less as its fireboox is 21’’W x 17.25’’D or just use it as a east west loader and your wood can be 20" .
You said your well insulated house is approx 650 square feet upstairs and approx 650 in he basement and the stove will be in the basement. And the basement has insulated walls.
They say you can always load small loads in those larger stoves, I have not experience with that. Too help you out on that aspect.
All those stoves work in the basic same way with secondary air up top. I think performance would be comparable but the big fire box will give you longer burns and more capacity but may get the room too warm at times.
If your going big and are looking Drolet , the Austral or Myriad is more of a square box to hold the standard 18" splits N/S or E/W configuration of wood loading , thats the size of splt most people sell.
The Austral and Myriad firebox dimensions are 18.5 " W x 21.25" D.
One thing to point out, I read that the Myriad and Austral are true N/S loaders which when you load that way the wood can burn hotter and faster. So what I read was that these stoves dont have a doghouse air so as the wood burns more even in the N/S configuration.
North/South loading is preffered as a way to not worry about splits rolling out on you.
