Thought I'd check in as well, just made it through my first 2 weeks burning coal and it's been pretty great!
I will be starting to use Blakshak coal as of tonight as the original bags of "unknown" coal I got at the hardware store are depleted. I'm still having to keep my air inlet open more than most of the rest of you (1/2 to 3/4 to get a good hot burn), haven't really figured out why yet. I also noticed that my flue pipe measures just under 300 with the damper closed, this also seems a little hi compared to what I'm seeing here.
Over all though I am easily getting 12 hour burn time's and running about 50 lbs of coal through in 24 hours. Griddle temps are usually between 490 and 550. I can't go much above that as we are roasted right out of the room.
I have ceiling fans and box fans and a tower fan all trying to get the air moving but it's not been that successfully so far. I think I need to get some door way fans and try and get a circular motion started. The Oil has kicked on in the mornings a few times but It doesn't bother me too much as I want the oil burner to stay in decent shape and my dirt floor basement can get pretty damp if I don't blow some hot air down there now and then.
BTW I paid $195/ton for the Blakshak at the Pine Grove breaker (Don't think it's a breaker anymore just a bulk seller) I went there because it's only about 15 min. and didn't want to drive up to Mt. Carmel, maybe next year.