When I had my EPA insert installed I had the place that I bought it from install it to extend the warranty. I have a full masonry chimney and they installed a smooth wall stainless liner inside the chimney. I do not get a lot of creosote buildup , maybe a pint every two months, which is my cleaning cycle. At the time I asked about an insulated liner but was told they do not do that in my area. Now that I think of it, my bet is that my liner would get hotter and have even less creosote if it had been insulated. The masonry surrounding the liner is not going to insulate as well. The EPA insert takes so much heat out of the fire that at my chimney cap the gases are often just warm. I run it 24/7 including getting up every 2 hours at night to load wood, so there is no morning warmup where I let the fire flame up. I do periodically open the bypass when I need to generate some coals (if I let it burn down too far) and let it go for 30 minutes or so. The EPA stove takes more smoke out of the gases for sure but mostly on a Big Hot fire and that will drive me out of the house on moderate weather. I often run hot but small fires which does not get the CAT glowing. I only burn wood under 20% humidity. With our cool/cold damp climate our firewood only gets down to about 17% moisture when stored outside. We seldom ever have freezing weather, just damp day after damp day in the high 30s, 40s and 50s with air averaging 80+% humidity. How dry does everyones wood get?