I'm not sure if I should save all settings to ini file

[plumberrob]

is there an advantage to saving all settings to ini file instead of registry ? 

[nukecad]

CCleaner.ini saves all the changes you have made to the settings and any Includes/Rxcludes etc that you have set.

It can be handy to have that (and make a backup of it) so that you can quickly restore those settings if needed.

examples:

• If you have had to uninstall CCleaner completely then a new install will read the CCleaner.ini file and restore all your settings.
• If you install CCleaner on another machine you can copy/paste your CCleaner.ini to the new machine and save having to set it how to you like it from scratch.
• If you have changed your settings and want them back as they were then you can copy your backup .ini to replace the changed one.
  (That's something I do frequently after changing settings when answering queries here, It's the quickest way to get my own settings back).
• Advanced users can edit the CCleaner.ini to add extra commands and extra cleaning in there.

Advanced use: https://support.ccleaner.com/s/article/using-ccleaner-ini-to-modify-how-ccleaner-runs?language=en_US

Note that CCleaner can also read and use other .ini files as well as CCleaner.ini
https://support.ccleaner.com/s/article/what-do-ccleaner-for-windows-s-ini-files-do?language=de

The most commonly added is the user created/maintained "winapp2.ini" which adds cleaning of many apps that ccleaner does not clean by default.
If you might be interested in that then it has it's own section here on the forum, (you can see it's been running since 2010 and is well established):