Anything patched for spectre and meltdown seems to have issues on this machine...

4.4.0-83 is, as mentioned working as it should;
4.4.0-154, latest auto-updated on this series doesn't boot;
4.4.0-185, latest from mainline on this series doesn't boot;
4.14.133 installs, obviously after manually pulling libssl-1.1, and boots but, it has issues with ACPI;
4.15.0-54, boots but, with wrong screen resolution.
Anyway, the system is now back on 4.4.0-83 and I've stopped kernel updates, everything else will still be rolling in as usual.
Not the solution I was looking for, but I won't bother with it anymore. Even if I get another kernel to work, there's always the risk that a coming update will screw things up and I won't be around to fix it.