I haven't heard the Aperions but I am curious to read your opinion compared to the M80s.

I haven't bi-amped but if you hear a difference on the Aperions it's likely improved lower mid-range. That's where the Aperion is hardest to drive. If you are using a sub, you may not hear any difference with the M80s when you bi-amp them.

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