Never really cared much about DOpus and even less about Magellan. Had it installed for a short time when the key got available (was it on some old Aminet CD??) and found it confusing (which kinda goes hand in hand with every powerful tool).

Having dedicated source and destination windows sounds weird and would complicate break many things that work just fine for most users.

A dual lister window that is kinda both an Ambient view and a DOpus(4) clone as a 3rd party class seems plausible.