First year burner here with a Keystoker 90K. I will say this...if it was "super dusty" my wife would be beating me daily.
Yes there is dust but like Greg says, it depends on what you do and how you do it. Out in my shed/coal bin...lots of shoveling to fill those 5 gallon buckets to transport into the house, therefore lots of black coal dust. In the basement where the burner is, there is dust but you have to look for it. We haven't dusted the basement the whole heating season yet. Dust from ashes...I vacuum everyday. I make it part of the evening ash removal chore...takes me less than 5 minutes to add coal, remove ashes, and do a quick shop vac of the area. No extra dust upstairs in the living area.
I will say this though...I didn't know about this web site before I bought my Keystoker...If I did know about this site, I'd have a boiler outside.