The original fedup – 0.7 – did not work. Upgrade to 0.8 and then it complained about three packages – gthumb, picard-freeworld, and kipi-plugins. I THINK what happened is that my Fedora 19 version was the same or greater than the version in Fedora 20, but the dependencies were written in such a way as to not allow greater library versions. In other words, depends on library 1.0 and so version 1.1 doesn’t work. Sometimes that can be an important hedge against APIs changing, but often it can lead to annoying upgrades and updates. There are times where I couldn’t update a bunch of packages because of another. So I would remove that one and upgrade (or update) and later I could reinstall it. So I removed these packages and proceeded with the upgrade. It still complained about nvidia (which is really the only thing that is a problem after every upgrade)
Afterwards no major issues. nVidia still amod-compiled itself and I was able to reinstall those packages. Not as seamless as the last upgrade or two, but still in the top 5 easiest.