Apple is changing their privacy settings for iOS6 and deprecating device UUIDs (UDIDs). According to a WWDC presentation and the docs there are two replacements for the UDIDs, both in the UIDevice class:
-identifierForVendor
- ID that is identical between apps from the same developer.
- Erased with removal of the last app for that Team ID.
- Backed up.
-identifierForAdvertising
- Unique to the device.
- Available to all applications; used for advertising — iAd has converted from UDID for iOS 6 and later.
- Reset with "Erase All Content & Settings".
- Backed up.
It seems to me that -identifierForVendor is inferior to -identifierForAdvertising since it would get reset on last uninstall of an app from a vendor and by "erase all contents & settings".
What advantages does -identifierForVendor have over -identifierForAdvertising?