Worthwhile to add 2nd-gen Eero to current 3-Eero setup (version 1 Eeros)?

Is it worthwhile to add a single 2nd-gen Eero to my current 1st-gen 3-Eero setup, replacing one of the current Eeros? I have a separate cable modem, with the primary Eero operating as the router. All 3 Eeros are connected to the primary Eero/router by Ethernet cable. These 3 wi-fi access points provide adequate wi-fi coverage for a large two-story home with a separate room over the garage.

There are 18 connected devices - 3 computers, 2 iPads, 2 iPhones, 3 Apple TVs, printer, Envisalink securtity device, Amazon Echo, Logitec Harmony remote hub, Tablo TV device, etc. One of the AppleTVs is the newer 4K version and is used to stream 4K HDR programming. All of this works well for the most part, but when my adult son and his family of 3 (all with iPhones) visit, he complains that my wi-fi is not adequate for him to play games on his iPhone.

Does this indicate that I am at the upper limit of my wi-fi bandwidth for this number of devices? Would it be useful to replace the 1st-gen Eero router with the newer 2nd-gen tri-band Eero? According to the Eero support FAQs, the 2nd-gen Eero works well in the same network with the 1st-gen Eeros.

Any thoughts?

If you are using a wired backhaul connection to each Eero, I don’t think there is a need to upgrade any of the devices. My understanding is that the new capabilities are essentially an extra back-haul radio and the thread radio for IoT devices. Wired backhaul should trump the extra radio in performance and I don’t think there are any devices yet using the thread radio capabilities.

That being said, when I wanted to add a little more coverage outside of the house, I bought a gen 2 Eero and beacon then replaced a gen 1 Eero located near where most of my IoT devices reside and moved the gen 1 to a satellite location. I don’t think it helped now but might down the line.