this is what made me convince to go for octa.
Samsung S4 - Key Differences Between Quad Core and Exynos5 Octa versions | Fingers On A Screen - Smartphones, Tablets and more....
Here's also a detailed explanation of how octa works:
Samsung Galaxy S4 processor: how the eight-core CPU works (Wired UK)
Here's a video version of the 1st link:
Galaxy S 4: Octa-Core vs Quad-Core - YouTube
I could say the s4 octa is ready for future apps that demand more processing power, so multitasking will be breeze with it.
Anyways, mahibaw-an rana if makahands-on na jd ko sa octa.