Just remember, the device is everything when it comes to temperature control, there's no room for error, so the device has to be built with the correct wiring, good soldering robust battery connectors and a very good 510.
As a DNA20 and 30 builder, my first builds on the DNA40 had me questioning the same thing about TC, but I hooked up with a very respectable group of modders here and worked through the issues (some of which were Evolv's with the first iteration of the DNA40, [firmware and hardware issues. Numerous boards had to be RMA'd back]) ,and now though I still use mech squonkers, my best and most consistent vape comes from a TC mod.
As a DNA20 and 30 builder, my first builds on the DNA40 had me questioning the same thing about TC, but I hooked up with a very respectable group of modders here and worked through the issues (some of which were Evolv's with the first iteration of the DNA40, [firmware and hardware issues. Numerous boards had to be RMA'd back]) ,and now though I still use mech squonkers, my best and most consistent vape comes from a TC mod.