It is very hard for any of us to predict an answer for you. Even if a Kodiac owner can share their experience, there are variables with the chimney, coal quality, ash content of your stove, infiltration leak rate in your home, and many more I'm sure.
If you have a good draft from your chimney, and can dial down the stove low enough, then, as you mentioned, the ash blocking air flow through the grate will be the limiting factor.
I'd venture a guess that yes, you should be able to maintain a warm home with your setup. In cold weather, the chimney will draw better and keep air pulled through the coalbed. If you have a day that warms up and stays warm, say goes from 25* to 45* by evening, and your chimney doesn't draw enough to pull combustion air past the air control, then you might have a very marginal or out-fire 15 hours later.
One thing you will probably encounter is the problems with shaking a cold fire. Usually this is a major mistake. The coal in a firebox that is nearly burnt out is pretty fragile, you will need to open up the air control or the ashpan door and let the fire get cookin' real good before you shake the ash down [don't forget to close the ashpan door!!]. Then you can add some fresh coal to get the fire cooking again. If you shake down the ash too soon, then the fire may just go out, and you have to start over again.
Hand feed or gravity feed stoves can be a balancing act between shaking, feeding, air control and draft. Your particular setup will require you to learn what it likes and doesn't like. This will change with the weather too. A cold front coming in with high winds and colder weather will increase the draft in the chimney and creat different burn characteristics.
It will be a fun learning process, Greg L