I got LMTX running on macOS Catalina.  I followed the directions here for versions prior to Catalina, including authorizing the mtxrun script through Security & Privacy General tab.  The first run of install.sh stopped with the errors:

cp: cannot stat '/Users/tkb/context-osx-64/tex/texmf-context/scripts/context/lua/mtxrun.lua': No such file or directory
cp: cannot stat '/Users/tkb/context-osx-64/tex/texmf-context/scripts/context/lua/mtx-install.lua': No such file or directory

So I ran install.sh again.  This time it said a bunch of things were missing and downloaded them.  It seemed to finish ok, so I ran context on my document and it produced a PDF!  (The ConTexT with TeXLive 2018 and TeXLive 2019 both died on this document with different unhelpful errors, by the way.) 

Both LMTX and TeXLive 2019 ran 5 to 10 times slower than TeXLive 2018, and both complain about "fuzzy paragraphs" with a list of U+XXXX codepoints.  What's that mean?

However, the PDF has unwanted whitespace in many areas.  
  • It has unwanted whitespace between the entries in the Table of Contents.  
  • It has unwanted whitespace before and after section headings, despite me having "before={},after={}" in the \setuphead commands for all the levels of sections.  
  • And it had a large unwanted white space between paragraphs until I \setupwhitespace[none]. I'd prefer a little bit of white space between paragraphs, but I tried \setupwhitespace[0.5ex] and \definemeasure[between][0.25ex] with \setupwhitespace[\measure{between}], and \setupwhitespace[5pt] but all those went back to way too much white space between paragraphs.
Any ideas?
--
T. Kurt Bond, tkurtbond@gmail.com