Ten hours left, it reckons, after days of messing about with DVDs & CDs. It wanted to spend 2 whole days downloading stuff when I tried the CD (the DVD part of the drive is broken), so I copied the DVD via my laptop & ran the upgrade from that.
That worked, up until about ¾ of the way through it suddenly wanted me to “insert” the DVD media — & I have no idea what it was triggering on, so I killed it & restarted it again on a real CD. That worked, until it complained that there were about 40 files missing because this was not the real DVD... so I copied the list of absentees, shoved them through a quick BASH script, & duplicated them (cp -a) into the APT cache directory, then restarted the upgrader from the CD again. Which seems to be working (it’s unpacking & setting up .deb files) but as it says wants another 10 hours to complete.
I have no idea about whether it’s going to try downloading a few more chunks as a part of that, so dialup stays on (/ME waves).