Easy. Lower frequency capability of the 6.5" driver vs. the 5.25" driver.

Too often people think that Atmos works OK with tiny little overhead speakers. That isn't the case. You actually want some good sized speakers (within reason) to be able to handle as much of that mid-range frequency as well.

I was at CEDIA several years in a row (starting with the last one before Dolby announced Atmos for the home), and each year after the Dolby announcement, more and more refinement of proper setup techniques and hardware usage would happen.

Outside of that first year being blown away by it, it was 2 years later that I experienced a Denon and Marantz demo where they were using overhead speakers with 10" woofers in them. Holy crap was the impact (pun intended) amazing. In big action sequences, having that sound energy able to come from overhead was quite noticeable. You are getting into some pretty low frequencies that normally would be handled by a sub, but being able to still be high enough that you can tell the direction it was coming from.

As such, I wanted to use the Axiom speaker with the biggest woofer that I could mount on my ceiling. Thus the M3 (M5HP would be nice, but didn't exist at the time, and at nearly 2x the price of the M3s, wouldn't have been in the budget. I mean, I was replacing (4) QS8s with M3 onwalls and adding 4 more for the ceiling. That was almost a $2000 sticker price on the M3s alone just to add Atmos plus the price for the Anthem MRX-1120 to drive them all. My wife would kill me today if she really knew how much has been spent on the home theater over the years.

Farewell - June 4, 2020