Been wondering about this myself. Only difference w/ Z790 is 12 -> 20 PCIe4 lanes (+ 16 -> 8 PCIe3 lanes) and somewhat higher supported memory speeds (though I’m not sure how much this part matters). PCIe lane difference shouldn’t matter unless you want more than 4 NVMe slots (CPU has 4 lanes for a total of 16). Meanwhile you can get a like… MSI Z690 ACE for 250$ which is currently less than a Z790 Tomahawk Max and much higher end.
They’re getting there… Most of the discussion I’m seeing on pull requests is small things now. Apparently some got improvement already by patching xwayland n’ stuff with the WIP patches, but it still requires compositor and driver side changes to be fully fixed.