I dont see any reason to go for the third gen in terms of real world performance. I dont give a rats a** about heat or power usage, my power supply and liquid cooling will more than compensate for anything like that.
This question would easily be answered by reading one of the many reviews. They all address this question directly actually. Or were you just trying to start an argument?
If you don't have a Sandybridge already it is worth it to go to Ivybridge. If you already have a Sandybridge then probably not. There are a couple of new architectural improvements, new RAND instructions and a new IGP but that's about it
i would only get ivy bridge if you are going to get a z77 mobo, other wise it would be fairly redundant IMO. i have a i5 3570k sitting on my shelf waiting for the full ROG ATX motherboards to be released.
This question would easily be answered by reading one of the many reviews. They all address this question directly actually. Or were you just trying to start an argument?