What do people feel about wrapped vs. poured insulation for stainless chimney pipes? I have a 7" X 11" flu, and need a 6" pipe. One outfit has a smooth wall stainless pipe they use with a poured insulation...life time transferable warranty and the tiles stay in the chimney. The other method I'm looking at would be to remove the old clay liner and use a flex pipe with wrapped insulation. I'm just curious what the experts here think of both systems, pros and cons, etc.