A certain and at this point, unknown amount of tobacco specific nitrosamines would indeed likely be present in NETs. And yes these are carcinogenic, but as stated by the OP, at far less concentration than in cigarettes according to the limited research that has been done that I've come across. And true, it is about harm reduction for many of us. Combustion of tobacco introduces a number of carcinogens in addition to the TSNAs as well, so generally, vaping, even of NETs should provide significant harm reduction. This will eventually have to be proven of course, but it's common sense. Less TSNAs than smoking, and fewer, or even none of the other carcinogens created from combustion, so should bear out as less harmful. Will further study show that vaping synthetic flavors is less risky than vaping NETs? I believe it will, but I can 100% say that for me, and I do believe for several or many others, NET vaping has finally kicked me of the smoking habit all together. No "lab" juice that I tried before or since quite does it for me in the way that NETs do.