My hair system salon dyes my hair if / when needed
I also dye my system myself when it fades. It's really easy: just be sure to leave around 1cm from the base so that you don't risk dying the UTS/lace. And leave on for only half the recommended time - assuming you are using normal hair dye like L'oreal etc
I'd only use Back2Natural conditioner if my hair system colour fades.
I personally wouldnt risk hair dyes as I've had severe allergic reactions to things before. Although its on a hair system, when its washed the dye can get on your skin.
My boyfriend also often had his hair painted at the barbershop. It looked good on him and I would have never guessed he was painting his hair. His barber went on vacation and he was looking for another barber. He found something good on https://nicelocal.com/nearme/beauty/type/barbershop/ and not far from our house. Now he only goes there because everything is wonderful there and close to our house