PJ48: ...
This explanation of s true mesh controller system makes them sound very desirable. Do you know if the Unifi controller system with hardwired Unifi access points also works like this?
Yes that's how Unifi controller works as well. The controllers for different mesh systems vary in how well they do this and how many mesh support features they support. There are a number of optional specifications a controller/AP/client can support to improve a mesh network or roaming for examples 802.11k, 802.11r, 802.11v. Depending on the mesh system or controller some of the functions maybe disabled by default and you may need to go into setting to enable them. For example fast roaming (802.11r) can be disabled by default on older mesh networks as there was compatibility issues with old clients.