I only use VW mode because I simply prefer it to the times I used various TC coils/materials on different devices. With that being said, there hasn't been a slight issue using dual LG HB4 18650s and charging them in the device via the USB cord. The internal charging is a selling point of the device so unlike the RX200S, it doesn't specifically mention a recommendation for using a charger at all, though it's probably smarter. I use my XTAR VC4 charger but will definitely use the USB if I'm in a pinch. I think the ability to lower the ramp up time for firing (immediately reaching targeted wattage) or slightly increasing it (TCR I think it's called) for vaping 180W so it's not too much to handle in one millisecond blast in your lungs. I cannot say if or how the TC modes work but if you like the feature I described, which many do, grab one for under $49 bucks online and don't read negative reviews unless you're concerned about TC functionality.