Boom. I don't think that anyone is doubting that having a basis to test against is not important. I think what is trying to be said is that sensitivity number is just a delta number to start with.

The problem with just using that number is it doesn't tell you quite enough about how the speaker will perform in real life as it's only a single point measurement.

In your case, you are going from an M80 to the M100 and the general impedance between the two speakers are similar if not better for you with the new speaker.

if the sound limitation you were getting with the M80 was due to the amp simply running out of power to drive the large woofers rather than a limitation of the amount of surface area of the drivers themselves, then your sound requirements wont be met with the new speaker.

This is where the devils advocate pointers come into play with pointing out that if you are looking to play music with mostly deep bass then your power requirements will be substantially more than the calculations that you gave,

Anthem: AVM60, Fosi DAC-Q5
Axiom: ADA1500, LFR1100 Actiive, QS8, EP500, M3, M3comp, M5