I’ve successfully upgrade my laptop to KDE Plasma 5. I look forward to exploring. There was one small hitch with the display manager. Despite prompting me to select between LightDM and SDDM, the system came back from a reboot with LightDM. LightDM doesn’t know how to start up a Plasma 5 session, apparently. Quick thinking saved the day, I simply stopped the one and started the other manually and all appears to be well. Still glad I did this on my laptop rather than my studio machine.