Rolled back to the previous version (3.0.0.4.388.21709) on the AX86 Mesh nodes, leaving 388.1 on the AX88 - back to stability/predictability. Still, more often that not, getting better WiFi throuput connected over the AX86 Mesh nodes (wired backhaul) vs the AX88 but still much more bandwidth than is needed by any one specific device at any given time. Have the 2.4 and 5Ghz radio on specific channels, setup for 160Mhz, 802.1ax, SmartConnect(default settings) - all of it healthy again. Cameras and Tablets that monitor them have not lost connectivity or moved (even thought bound to a specific AP) to another AP since the downgrade. 5Ghz radio's on the AX86's much more stable, with as strong or stronger signal than the 2.4Ghz radio (based on Android Tablet having 2.4Ghz & 5Ghz with the Wifi Analyzer app). Devices that support both frequencies gravitate and stay on the 5Ghz radio again.
Just after the post I made, things went bonkers again - AX86 dissappearing, devices losing connectivity and moving around, devices dropping connectivity. But with everyone/everything online the quickest way to quasi normalcy was to down grade the mesh nodes. I did notice that while I have the 5Ghz fixed on Channel 36 on the AX88, and it's cleared for Radar (36/160) - at some point it switched to 44/80. A quick restart of the 5Ghz (Channelhog/scMerlin - either) fixed it (on the AX88, don't know if AX86s switched as well), still odd it switched with it fixed (rarely get radar interference, unless Police flying overhead, also rare).
While still not a 100% perfect, it's stable enough for the family not to complain and IoT devices staying online, more importantly I haven't had to touch it since. Thinking I'll stay with this setup for awhile...