I did not know rigid liner existed until today when my dealer mentioned it would work in lieu of more expensive flex pipe in my installation. This is because my chimney is a straight drop all the way down through the flue and damper. He was originally recommending a copperfield 304 flex pipe but says he could sell me 6x48" sections of 304 stainless rigid pipe. I see at least one online retailer sells this pipe as well as sections of insulation that snaps tightly around the liner. This looks cheaper than the flex liner and allows me to get it insulated as well. Any thoughts on this over flex pipe?