As others have said, it's purely a judgement call. If you're happy with the end result, then who's to argue.
Can't go wrong with the Maverick wireless therms. Some individuals have had issues.
But, I have a ET-73, as well as the ET-732 and they have performed great.
I have only been cooking on a Weber kettle for the past 3 yrs.
I, like Duke, have been getting away from gadgets once I cooked more and more on the kettle.
Depending on my charcoal set-up, whether it be the snake, baskets, Minion method, etc, I like to know the temp.
So, I use a gadget ... initially. Once I have an idea of temperature in relation to the intake vent settings, then I toss the gadget aside.
I, too, believe that the dome temperature reading is quite different from grate level.
My go-to temperature reader is for meat only ... my Super-Fast-Orange Thermapen.
Ultimately, you do what you feel is best.
JM2¢