Im going to be using one of these CPUs for Rendering, I need them to be Working 24/7. I dont know if the 3770k is worth the extra money, but I will be overclocking (4ghz) Im planning on using the Noctua NH-D14 Cooler, So I Need Low temperatures All day long.
The 3770k should be fine for that. Problems only start past 4.5, and the Noctua DH-D14 is PLENTY to keep it cool.
The 3770k is slightly more efficient in its cycles, but the biggie here is power saving... it uses less power, and you're going to be running 24/7. Sure, the money you save on power isn't THAT much, but then again, neither is the price increase from a 2600k to a 3770k.