I use a Flint 2, I think I have something like 5 AP’s On it and it covers my whole home. I have a bunch of vLANs as well for the APs and VPN’s. It came with some custom OpenWRT install but I flashed it with a vanilla version instead. I was using an Apple Airport Extreme prior to getting the Flint 2, but my place flooded and I got board so I took up the hobby of home labbing while I wait on insurance to get things rolling (after a few months the flooring is finally going in tomorrow) my original plan was going to be use the Airport as an extender but I did not need that, but yes APs with the same SSID will work together. My Flint 2 has SMB setup to back up its settings to a pi I have on my LAN.