Sorry.
On a Protank II with a 1.8 ohm stock coil, 3.3V on a Spinner, so 6W.
On a Russian 91% with a 1.7 ohm coil on an SVD, 9.5W.
The difference is due to the different wicking efficiencies and the sizes of the
coils, as well as the details of the power supplied. Even with the same
tank, I change power between the Spinner and the SVD.
Neither of those is dual coil, but with a range like that there isn't going to be any meaningful difference. Theoretically, with dual coils and independent wicks you should be able to double those powers, but I bet you can't.
That's with the same liquid -- HS Delight. Different liquids will have different optimums too and different people like different notes from the same liquid, which means their personal tastes make a huge difference.
Experimentation is the only way. And some liquids just taste horrible no matter how you vape them. Then if you get a better atomiser, you can find that you don't really like a liquid that was your favorite in your previous set-up, because you are now tasting more of the true flavour.