I don't think this will be if much help but, from what I understand, the catalytic thing (not sure exact name) is something in the newer inserts that further burns the soot and particulate matter so less smoke comes out of the chimney, thus a cleaner burn. But as to why the contractors told u yours is junk, I have to wonder what makes them think that. And I completely agree with u that salesmen (in general, not all of them) don't always have your best interest as their priority. I don't have an insert just an open fireplace. I burn wood all winter long, about 2-3 cords worth. Maybe someday I'll get an insert when I don't want to have to find/buy/cut/store so much wood. As for now, I enjoy splitting wood almost as much as mowing the lawn so I'm not in a hurry. Back to your current insert...is there structural damage to it or something that led the contractors to believe it's junk?