Doing first upgrade with hacks

[da420]

You should not be worried. It was very simple for me.

Here is what I did.

MAKE BACKUP.
Disable products.
Upload file.
Run Script.
Revert templates and fix them.
Reenable products one by one.

That was what I did. When going from 3.6.1 to 3.6.2 I didn't even disable my hacks, and everything worked fine right from the get-go. No need to worry as upgrading has been made really easy.