Twenty-two hours that took. Good grief! It copied all 1000 gigabytes of data from the old dead disk, and then sat there trying to rescue the 300-odd megabytes of lost or corrupted data from the bodgy bits of the disk surface. I ctrl-c'ed it, at that point, and mounted the disk image to make sure it was OK. It was, so now I'm copying the image to the new drive, and it says it's going to take another 14 hours at least.
It's certainly a very clever program -- would have been cleverer if it enabled logging by default, since I forgot to give a command line filename for a restart log -- but it could do with some optimising. I can't believe it really takes nearly a day to copy a terabyte of data. It's writing at less than 20 megabytes per second, which I'm sure is bogus. Where's Andrew Tridgell when you need him?