The image here is what I currently have - an Airport connected via ethernet (got my top floor wired with cat 5e, using a network switch) to 2 other Airports around my house. It works good but is older now.
The Nest Wifi Pro is on sale now, and I’m looking at the 3-pack. I’m wondering if there’s any benefit to connect these together via ethernet like now, or if the mesh network is faster/better?
Ethernet will always be better than mesh.
Ethernet does not negate or negatively impact Mesh. The largest benefit of a Wi-Fi Mesh is one consolidated SSID with automated roaming of mobile devices.