On the strength of your recommendation, and an unwillingness to wait for the arch repos to update emacs, I went ahead and installed the master branch. So I'm now on version ... 27.0.50. Skipped 26.1. :)
As you said, the change was smooth and I got to enjoying all the new fixes and stuff. But my word, it was over a gigabyte of downloading, which I didn't expect! Still, worth it.