80hz is the most recommended from most AVR. manufacturers especially those with the THX certification.
It is essentially setting your speakers to a small setting though the biggest of small. Which itself is good since you have subwooferage for the low notes.

I myself have the M80s and a EP500 as part of my home theater. Was previously an Onkyo and Integra user those A.V.R.s would always set all my speakers to 40hz. almost cancelling out my subs I usually reset them to 60hz since I use an external 3 channel ADA1250 have no worries of power with lower setting.

Now in the last week have joined the Axiom/Anthem club which the Anthem MRX720 finally set my crossovers to 80 itself?{weird first time}

With your external Amperage. you could safely have crossover as low as you want without any power concerns. Unless you have it at 11 continuously.

Congrats

This is quite an interesting thread as most of us have been mentioning a showdown of the 2 brands for quite sometime now.
Although not a showdown a fun read