Speed drops materially between devices even in the same room. Eero connected to the modem is getting 470mb/s speed, output from that unit on Speedtest is about 200mb/s. Second eero within a few feet only puts out at 30-60mb/s on Speedtest. There’s no way that I can find to make the units all get similar speeds as the connected eero.
Also be prepared to pay extra for some silly subscription that isn’t included with the devices.