Hi, just found another local pellet stove place...my fifth one I've visited. I had it narrowed down to st. croix or avalon. However this company has been in business for 31 years and they will be there another 31 (son installs pellet stoves). They carry quadrafire. Now the quadrafire carry aluminum heat exchangers. Is cast iron or stainless steel better and if so how important is this to the longevity of the system. My father in law tells me the stainless is better but now I'm so confused I'm not sure if he was talking about the heat exchangers or another part that should be stainless steal or cast iron. After all said and done we would save about $4 -500 if I went with the quadrafire. I live in poughkeepsie ny. Thanks!!