I wish Beth would give us the option of updating - ah well, back to the old rigmarole of downgrading manually.

Does anyone know which files need to be restored to return to version 1.7?

Kind regards.

Use Windows "previous version" of your skyrim folder feature.

Update.esm only, save the current one somewhere to explore its features in game though.

I personally prefer restoring the whole folder. To each is own I guess. Doesn't hurt to make a save of the game before updating either.