I updated to Mojave today. The update took about 1 hour 15 minutes and the important things seem to be working. Entourage 2008, my preferred email client, is fine (it's 32-bit). The one glitch that I noticed, so far, is that the update did not recognize Epson printer app. I located it in a clone and copied it to ~/Library/Printers. Printing now works. I don't know why it had disappeared from that location in Mojave.
Naturally, I backed up everything before updating (and a good thing, too).