Illuminated switch/ LED with DNA20

[Vapant]

I would like to fit some illuminated switches/ LEDs in my wooden DNA20 mods, that light up when the button is pressed.

I like these - 12mm Illuminated Vandal Proof Switch BLUE
"The switches LED is 2v and 50ma so to avoid blowing the LED use a resistor in series with the LED somewhere around 100ohms at 4.0-4.2v or 300ohms at 8.0-8.4v"

I calculated the resistor needs to be 1/4Watt 47 ohm LED calculator for single LEDs
Stealthvape sugest around 100ohm @4.2V

I figured that if I powered the LED from the dna output I couldn't have a nice bright LED at 7Watts incase I accidentally pressed the fire button at 20Watts so I've decided to power the LED from the Battery instead.

Is this an efficient circuit?
I've been using it for almost two months now with no noticable drop in battery performance or excessive heat (that I'm aware of)

Thanks
Ant.

Edit- The Transistor is a PN2222A by the way, I forgot to put that on the drawing.

 

[Vapant]

42nd day bump (Worth a try)

Does anyone know, Is this ^ an efficient circuit?