I think both these options have one potential pitfall, which is file
ownership after the copy over of stuff I want to salvage from the outgoing
HDD. If I do a fresh install, no guarantee that user IDs will be the same
on the new system as I of course don't remember now what order I installed
stuff in. My regular user ID created during install will no doubt get the
same ID (although even that is not guaranteed as this machine started life
as etch, if I remember rightly, then was upgraded to squeeze, then to
wheezy, and finally to Jessie). And I don't remember exactly when I
installed, for example, mysql in relation to other stuff. So I could have
some fun and games copying stuff over from the old disk to the new from
that perspective. Any clever ploys to deal with that?