This is an interesting thread, I recently replaced an old Franco B. with a Harman Magnum there is a difference between the two and as you are finding out it's hard to describe, first remember the size of the fire in the F.B. was much larger than the little plate of fire we now use and the F.B. was a constant radiant heat the stoker is up and down and relies on warm air a good bit .
That being said, while the room that the stove is in is not as HOT as with the F.B. the entire house is warmer from the coal and the room the stove is in is more even temperatured the oil heat has run very little if at all as compared to the assistance it used to give the F.B. .
Coal usage again is different as you know the F.B. used a bucket a day sometimes a bucket and a half when I say bucket I reference the standard black coal bucket available in a good old American hardware store, the Harman uses most days two of these and every couple a days needs three and there are mild days when it only needs one, you refer to 100 lbs of coal and I'm just not sure of that figure that would be two and a half bags of Blaschak coal,, but maybe .
Heres a shot from what I have learned about the Magnum, even in your user photo from as close as I can tell it likes like your firehead is still pretty far back on the grate I found that if I try to heat the space with too small a fire the thermostat just keeps the unit running continuously and you never get the desired effect (warm room),, see what I'm say'in . Try to adjust the feed rate to get the firehead as I call it, out to about 2-3 inches from dropping makes sure you give it time to stabilize between adj. before leaving the stove alone (hour or two).
QUESTION = Is combustion air adj. on these new Alaskans
I think your close on draft adj. judging by your stack temp but without a gauge it just a PURE guess experience helps in dialing it in even after setting the baro with a manometer .
I'd try to get a fellow stoker user to take a peek at it, cause it doesn't sound like you have a major malfunction but rather some tuning issues .