I have been running my insert for about 4 years with a 4 ' stainless liner into an interior terra cotta lined chimney with descent performance. Well, after being at a friends place and seeing how his insert performed with a full liner and roxul insulation on top of the insert I was sold! I purchased the liner from a local stove shop even though it was priced higher than the internet but available on the day I wanted it. Also I feel happy to give them my business! (keep it local) I have a 2 1/2 story home and needed 35 ' of liner. I left the liner coiled up on my shoulder and uncoiled it as I sent it down. It was an easy task with gravity doing most of the work. I had feared this job but had some luck that it went smoothly! After reconnecting the insert I insulated around and on top of the insert. I stuffed above the damper area with roxul, it made for a good poor mans block of plate. I also Insulated around the top of the liner just under the cap. The insert performs better all around! Faster start up,cleaner glass,hotter,longer heat output. Also I thought that I would loss some thermal mass due to the liner but the chimney feels warmer due to the fact that the heat that comes of the liner gets trapped in the chimney due to the insulation at the top of the liner and the sealed cap! Just thought I would share my observations. If anyone needs some Roxul I have about 8 4' sheets that would be sufficient to insulate or make a soft block off plate! Private message me. Im in Queens NY, keep warm!