Installed MATE via the mateslackbuilds git and uninstalled KDE via slackpkg. Anything else I should do to clean up what's left of K?
 

I recently switched from KDE to MATE. Installed MATE as per the instructions on the SlackBuilds git repo, and got rid of KDE via

It's been a smooth transition -- almost too smooth ... -- but are there any loose ends I should tie up with regard to KDE stuff that might have survived the slackpkg remove?

If you plan to use KDE apps someday, better to leave KDE installed.

Agreed. Unless you have a very small hard drive there's no reason to remove KDE in my opinion.