Thanks everyone for all your encouragement and affirmation that nothing will impact the cast iron. So far so good. My rig is not air tight so controlling it is a challenge. Even with the bottom damper closed it roars at 500+ degrees and chews through 15LB of coal in 8 hours. You need asbestos undies just to get near the thing!
Won't be a problem on cold night in January, but a bit too out of control for fall weather. I'm hoping when my barometric damper arrives (curse you Sandy!) it will help keep the fires or Mordor under control.
On the topic of MPDs... I know MPDs have been discussed ad nauseam in this forum, but can anyone tell me: If I had an airtight stove would an MPD in the flue pipe help keep heat in the room? Would an MPD or Barometric have any effect at all on a stove with truly airtight doors and airtight bottom dampers? Seems from all the forum posts that dampers are irrelevant on airtight stoves.