Ivy Bridge is designed for the energy crisis that is coming. The new thing is energy conservation. Compare the 2600 sandy to the 3770 ivy. Same processor. Except the Ivy does the same mhz with a little less power. Some complain about OCing a 3770 is not as good as a 2600. Well I have seed the worlds record over clock a 3770 to 7 ! On that note, if you have liquid nitrogen and are a freak then, you should shift gears to a hex core 3960k and be apeshit crazy when the Haskell or whatever it is comes out. 2011 socket you mentioned.
Look at it this way. If you are doing complex computations like trajectory to Saturn with a lander on a 10 foot by 10 foot area, you will need a computer that can take 6 days of computations and spit it out in 3 days. Saving hundred of dollars of man time. If you are playing video games or editing video I think even a z68 platform will get you there. I bet if you went up to hollywood you would see 3 year old computers doing the job. The 2600 is on sale this weekend for about 250.00 bolts nicely on a z77 platform combined with 32gb of ram and a nice Gpu you will not look back. That is my view on it. I came off of the x79 platform and a hex core after realizing that spending 1200 more on my rig then the z77 platform with 3770k, ssd drives and a quadro 4000 2gb GPu and only using 1/2 of the available space for ram. (16gb with 32 available) My computer edits video and whatever I want it to do. Sure I could spend that 1200 more and save myself 30 minutes of month in rendering time. But I go to the restroom or make a sandwich. Time management. If I want I can add another 16gb of ram and shave 10 minutes a month of it, I am sure. Hope this helps.
Both the platforms/chip sets are different but have advantages and disadvantages. Let me summarize.
1. The 1155 platform has dual channel memory while the 2011 has quad channel memory support.
2. The 1155 platform can set up a max of x8x8 sli/cfx while the 2011 can set up x16/x16 etc.
3. The sandy bridge along with the Z77 does not support PCIE 3.0 while the ivy bridge does.
4. SB requires lesser voltage and dissipates lesser heat then the IB while overclocking.
5. 2011 vs 1155 usually comes with at least a $100-150 overall difference while building( expensive RAM, quad channel etc)
6. IB performance > SB performance by around 5-10% in various applications. ( non overclocked)
Now there are different scenarios that you can use the various systems for. If you are looking to set up a massive tri sli/cfx system get the 2011 with its associated chip( 3820, 3930 etc). If its a single GPU don't bother. The 2600K vs the 3770K vs 3930 for example show similar performance.
If you are looking to overclock get a Sandy Bridge 1155 or 2011. Use good cooling.
Usually a 2600K at 4.5 GHZ is as good as or beats a 3770K at 4.0 Ghz.
Also have you considered the pile driver? Let us know what you are looking the system for and a budget and we can assist.