Chimney Liner Material 50/50 corn mix

Comparison of the two metals: http://www.bssa.org.uk/cms/File/SSAS2.25-Comparison of 316 & 316Ti Types.pdf
First paragraph on page two would cause me concern on the 316Ti as it doesn't seem to have as high pitting resistance... but it is purportedly better at higher heat. What's the cost difference?

From the manual (in case you don't have it yet):
http://ironstrike.us.com/system/doc...ginal/900139-00_A_PI40_EN_IICO.pdf?1430839189
Venting This fireplace insert is approved for venting with Type L and Type PL pellet vent pipe (listed to UL 641 and ULC S609) or listed pellet flex liner (2100HT [degree F.] liner listed to UL 1777 or ULC S635). The insert’s flue collar is 3” in diameter. The insert’s combustion blower pressurizes and pushes flue gases out the pellet pipe. All pipe joints should be locked together or screwed with three screws if the pipe does not have a locking system. The pipe joints can be sealed with high temperature silicone if there is a possibility of flue gases leaking into the living area. The pipe should be fastened with three screws to the insert’s flue collar. The longer the run of pipe and the more elbows used, the greater the resistance to the flow of flue gases. Four inch diameter pellet pipe is recommended for pipe runs greater than 15 feet or when a number of elbows are used. A 3-4” increaser can be used to connect the 4” pipe to the 3” flue collar. The outside air pipe may run up the chimney, horizontally, or down provided the structural integrity of the fireplace and chimney system are maintained. DO NOT INSTALL A FLUE DAMPER IN THE EXHAUST VENTING SYSTEM OF THIS UNIT. DO NOT CONNECT THIS UNIT TO A CHIMNEY FLUE SERVING ANOTHER APPLIANCE.

Another opinion: https://www.rockfordchimneysupply.com/blog-2/flexible-chimney-liners-explained/

http://www.olympiachimney.com/questions (down the page about 3/4)