Just updated the firmware and as I was exploring my newly acquired S4 (it's 1 week old today) I chanced upon the tab "Move to SD". *gasp*
So now I can shift some of the app/ app data to my external sd card!
Here's how to do it:
1) Go to Settings > More
2) Select Application Manager
3) Select an app that you want to move to your SD card
4) Click on tab "Move to SD card"
While I was totally trilled with this feature however, something bothered me.... where in the sd card are these data saved to? A mystery to be uncovered. ....