Was wondering about stainless steel chimney liners for a non-electric coal stove. Currently have a Franco Belge with a 5" stainless steel flex liner. Have burned the stove for 24 year without any problems, but the stove in now broken. Considering getting an Alaska Kodiak and will need to change to a 6" liner. One dealer recommended going to a Duraliner rigid insulated set up. Another said to use 6" flex. There is a $1,000+ difference between the two. My chimney is through the center of the house and I've haven't had any problem with draft. Any input would be helpful. Thanks.