I have decided to purchase a Buck Stove insert based on recommendations from friends and the reputation of the company and am not sure which would best suit my needs. I have a 2 story house (about 2100 sq.ft) with the fireplace in the basement (around 1000 sq. ft) which serves as the tv/play room. I intend to use the stove to heat the basement and to assist with heating the upstairs by heat rising through the floor and stairwell. I am looking at the model 74 and the smaller model 21. There is roughly a $300-$400 dollar difference in cost of the inserts. I am concerned that the smaller model will not be sufficient to assist with heating the upsatirs, but I like the smaller dimensions of this model as the depth of our existing fireplace is not that deep.