I have a drum dial thingy key. Not the one with the big honking dial on it - It's got the small wheel thingy with numbers on it.
Anyhow, I found it completely useless on vintage drums, or in my world, vintage Kent drums.
They might work on newer drums, with those sharp, new bearing edges but I find that on MY vintage drums, the tensions per lug are not always the same across the board. In some cases, you'll have some lugs which feel lose while others are tight. This could be due to many things - Bearing edges which are not perfect, lugs which are not perfect, and of course hoops, which are not perfect.
I just use my ears and my hands to guide me. Just my $0.02 on the subject.