Because of the wallpaper autofix disable, I'd like to try the beta 8.1, I'm just curious about the ease of reverting back to 8.0. Any caveats? Thanks.

DF dumps its settings on the start of a new build in a folder named "DisplayFusion Backups"
(though i don't know if it does that with the settings of the old build or if its already the state of the new one; since these in my folder always have the version number i upgraded to in the filename, i guess I'd need a dev to chime in there.)

if you don't want to rely on the automatic backup, you can do that yourself.
right click on the DF Systray Icon, Select Settings, in the opened Dialog select the Options Tab and click on the "Export Settings" button and choose a location and filename for the Settings dump.
if you need to go back, you will have to choose "Restore Settings" in the same Dialog instead.