Installed it on a Mac Mini (3rd gen i7) and after the install it sat on a blank screen (with mouse cursor), but a forced restart and all was perfect and everything is operating brilliantly. Fantastic treat that it is free.
If the display driver is at fault, grandparent wouldn't even see a mouse cursor.
I don't know anything about 'properly cleaning the kernel caches', but it's clearly not a problem since grandparent was able to continue by rebooting.