The power vent on our keystoker runs constant weather the stove is cranking or on idle to remove the exhaust fumes. Nice thing is you don't really need a large chimney, just a few pieces of pipe.
The electric bill probably went up a few bucks. I checked the power draw on the with a watt meter, I think it was around 180-250Watts most of the time. Our gas bill went down to next to nothing, since we didn't use the furnance and everything else was electric (Stove, Dryer, hot water tank).
gas bill from other house.http://nepacrossroads.com/download/file.php?id=206
Anything else just ask!