Carbon Copy Cloner works great. But it also doesn’t let you pick and chose files. I had problems with Path Finder and this very same setup years ago.Carbon Copy Cloner is a very effective GUI for rsync.
Update data point:
I can seem to copy one large file at a time, 50GB. However, if I copy two files, the copy appears to copy one whole file, but then the spinning beach balls occur before that file is usable and then never copies the second file.... well copy status bar never progresses.