Did you de-lid your Ivy Bridge? What you say about the processor may well be true except for their choice of TIM-goop instead of solder with the non-E processors. The only thing I can say again (with my SB 2600K): You may get high clocks; you may get Cinebench scores close to the Haswell 4770K; but there are enhancements to the instruction set and other features that you don't get with the earlier processor.
That being said: I still love my 2600K. As for your IB, that's pretty darn good -- 4.8Ghz with a corsair H80. My recollection of comparison reviews seemed to show my D14 falling short by about 0.9C from the H80, and I know that replacing the two Noctua fans with a single Akasa 140R gives me a 5C advantage over the review benchmarks.
Not delidded. I think I got a lucky CPU though. The H80 is so easy to install and takes little space. I dumped the noisy corsair fans for Scythe I had lying around and the machine is silent. They are in push-pull configuration. The only thing I can hear is the GPU and only when running an intensive game.
It's hard to say if I can get increases in performance from going to Haswell without trying but it seems the odds are stacked against me. I think I'd need 4.5GHz even accounting for better IPC and new instructions. It doesn't seem people are getting that with simple water or high end air. Haswell seems like an overclocking brick wall.