Its more complicated than that.
The modern bikes use them mostly to give more space, they have extra stuff and big air boxes to squeeze in.
The stick coils have a rating from 6v to 24v as on the manufactures websites but there is a different dwell time given for different voltages that I'm not clear on.
Also they are not pure resistors so the cbr6 one at 1.5ohm doesn't give 3 ohms when connected in parallel you get 2.8 due to induction in the circuit.
From these readings you can work out amps in the circuit etc but you will not get any gains apart from space under the tank.

The only advantage is getting rid of the high voltage leads between the coil and the plug. That's it. There is no performance advantage.

Advantage I found was not having to mount the coil packs, I didn't expect or notice any performance gains.