I want to flash a custom rom on my S3. I was wondering if I take a Titanium Backup of all the applications and data on my phone, would I need to re-register (sim verification) for applications like WhatsApp, Tango, Viber etc. even after I restore the data?
When you flash a custom rom and you are coming from different version of android, restoring app data may cause some problems. If you restore your Whatsapp's data may cause crashing that App. So its better not to backup data,backup just that Application. If you are flashing same android version it may not cause issues. And you don't need to re-register.
I played with fire and went ahead and backed up my data with TB, flashed a custom rom (ParanoidAndroid 3.0) and restored the backup! Well, this is how it went:
WhatsApp - restored the data without re-registration
Tango - re-register
Viber - restored
Google+ - log in required and configure the settings
Facebook - already logged in (but re-sync contacts)
Path - already logged in