I just did a fresh install of 5.1 from yum-test, and migrated everything from my 4.10 over to it. Everything went as expected, except a few things I noticed.
One thing to note, is to install the extensions, before start editing the data in them. I'm running Belchertown, and coping the skins folder over first was a bad idea. Just let them install and them tweak the folder as needed.
Seems this is supposed to come with v5? But did not for me. I did a dnf install, which was never done before on my system.
INFO weewx.engine: 'pyephem' not detected, extended almanac data is not available
Also, when I do a weectl database reconfigure, it doesn't use what is already in weewx.conf (like what configuring the hardware does), but wants to create a weewx_new database? That threw me for a loop, because I was trying to make sure everything was right, before I started it up for the first time.
Otherwise, all back up and running and can now archive my /home/weewx install.
Thanks!