The spec sheet claims "Dual WiFi radios" as well as "Simultaneous 2.4GHz and 5GHz wireless". This tells me you're probably using a pair of dual-mode 2.4GHz/5GHz radios if you can act in dual-5GHz mode.

Assuming this radio setup:

Do you dedicate one of the radios to the mesh communication?

If so, does this mean you have a non-simultaneous dual-band 2.4/5 on the other radio for client devices?

Do you intelligently switch the mesh radio between 2.4GHz and 5GHz on a per-access point basis based on what gives the best ratio of packet loss to bandwidth to the surrounding mesh nodes?

How many antennas do you have per radio/band?

That's good to know. I don't feel like my original question was answered though: why the Eero repeater would get a better signal than another good WiFi solution at the same location? How do you get a strong signal to repeat from?