Yep, the main Mint edition is always based on the newest Ubuntu edition. Usually there is a month or so of a few Mint RCs from the release of Ubuntu to the release of Mint.
There are nightly builds for Cinnamon, though.
Thank you for this thread. That’s all I can say. You most definitely have made this forum into something special. You clearly know what you are doing, you’ve covered so many bases. Thanks!