How about the best of both worlds?
Do the 1st step of the re-install method:
dpkg --get-selections > dpkglist.txt
& put the file some place safe. With luck you won't need it, but it will be available if you do. For additional protection, you should also do:
dpkg -l > dpkg-l.0.txt
stash this file in a safe place too.
You also should consider a back up of the system. Ideally, a gparted
clone into some unused disk space.
Then, allow the "let it happen by itself" approach to take its course. After you do the upgrade from the Testing sources, you can do
dpkg -l > dpkg-l.1.txt
& diff the 2 dpkg-l text files to see what is different that might need intervention.
If this easier way works, then great; otherwise, pull the saved dpkglist.txt
& continue w/ the re-install.
I think the dpkg --get-selections
to a list method is best for anything but letting Testing catch up to Unstable.
Please tell us what you decide to do & how well it works.