This is a tough question you are asking Boom.
You don't want bass extension yet you find that the subwoofer does add prominence to the sound (and it likely will).
We are talking basic physics.
More drivers, equals more air movement, equals more bass. Larger driver (typical on subwoofers) equals more bass more easily (with less power).

Frankly, you sound like you want to get rid of the sub and go with a single speaker set. If that is your intent then yes, go with M100s to maximize the bass output as you can.
However if you are on the fence about whether you will 'lose' something by getting rid of the subwoofer, you are correct.
You will lose low end bass extension and the ability to create bass with less power.

You don't need to have your subwoofer turned up to the point where the wife thinks she's having another child. If dialed in correctly at an appropriate SPL for your preference, you can keep the M80s and have a great sound reproduction to your liking.
If as mentioned you are intent on getting rid of the sub though, for either aesthetic or other reasons, then sure, consider the M100s as an alternative to "try" and maintain as much bass as possible.

Just fyi, 90dB is pretty damn loud.
I would recommend a sub in these conditions.

"Those who preach the myths of audio are ignorant of truth."