I've been running 16340's in handheld lights for the last six years.
I'm really not sure why this hasn't caught on? It's like its some kind of secret?
I have yet to burn a light up or blow up a single battery.
I had two sets of two 16340's in a rotation in my first light t-max for six years. This light was used and abused on duty. I would charge a set prior to each four day work rotation and run them dead by the end of the fourth day. Each set of batteries had hundreds of charge and discharge cycles on them.
The TLR7 sub can run just fine on a 16340. My X300's run just fine on 16340's.