Yes - this script does not delete/create/resize partitions. It just migrates wubi installs to existing empty partitions.
Yes using --no-bootloader will not install the grub bootloader. It will leave the windows bootloader in place. You can use the wubi grub menu to boot the new install temporarily - but this is not a good long term solution because you have to boot the wubi install to update the grub menu e.g. every time you get a kernel update on your migrated install.
If you are happy that the migration worked well, I recommend either installing the grub bootloader, or using an alternative method.
Bookmarks