Bob,
I recently installed a mesh system in my house. While the house is relatively small, it did have some dead spots with my old system. My old system was a router with a repeater. The new system has a router with two mesh devices. Coverage is complete but the reason I upgraded was to avoid having different networks for different parts of the house. Now I can "roam" throughout the house with no dead spots and not having to change networks. Note - It worked good with just the main router and one mesh device, but I decided to make sure it worked everywhere. Now I'm down to just two networks, my home network and a guest network.
Best,
Clifford