Thank you so much for the detailed reply! At this point, I'm inclined to go with the Duet Ethernet. I have hard wired ethernet available off a small switch right next to the printer, thus no need for WiFi.
I have an LCD with the encoder wheel, but I really don't like it very much. Going to a PanelDue of one size or another seems like a nice upgrade, even though the web interface may be the primary way to deal with things on a daily basis.
I had a question about the connection between the PanelDue and the Duet Ethernet. The way the FT-5 is designed, the two existing boards (LCD and SKR), are about as far apart as they could be (SKR at the back in the electronics box and LCD up front). It really won't work like that. You have to put ferrites on both ends of both ribbon cables to get rid of all the RFI interference on the display.
It still then won't reliably print from a file on the SD card. The only way I was able to fix that was to move the LCD to the back so it was close to the SKR, thus making the ribbon cables much shorter. Still needed the ferrites
So when I connect a PanelDue to a Duet Ethernet, can I have them about 20" apart and have things still work fine? Also, the interconnection wiring between PanelDue and Duet Ethernet: Is that wire going to be in the box with one or the other, or do I need to find such a wire link and order it separately?