I don't use flashlight charger: 4.11v charge max.
The 06 is gonna be good enough to carry even in my jacket pocket; and that's an EDC possibility.
Batteries such as Nitecore, AW, Eagletac, KeePower, Fenix are re-branded Panasonic cells, so yes, any of those are good and stand for their capacity.
I thought Fenix uses the Chinese BAK cells as reviewed by HKJ for the Fenix 2600mAh cell