I found in all of my rooms, the M100 would not disappear as well. But...larger images, more presence, wider soundstage, louder and higher fidelity than M5. The 1000-2 with M100 is a formidable pairing. 1000-2 with M5 not so much. Nonetheless, I take M5 over M100 because of the disappearance. But I want the 1500-2 with the M5.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated