But on the other hand, I'm not convinced the 3570K even "overtakes" the 2500K. I'd still like to see more articles about how the heat (if it does) limits the Ivy's final overclock. Link me if you have any info on it, I seriously would like to know.
I actually don't know of any links on that, just that from what I've read, a "safe" max OC on the 3570K is 4.3-4.5 without some high dollar cooling, when you can go 4.6+ on the same cooling with a 2500K and 5.0+ with the high dollar stuff.
I'd say Ivy would max out at 5.0 or so on "normal" cooling (custom water being loosely defined as normal) when Sandy would probably go 5.3 or so, if you could keep the voltage low enough.
Beyond that would require sub-ambient solutions unless you're really lucky. Talking about 24/7 OC's here, of course.
At those speeds, it basically equalizes the performance since 4.5 on Ivy equals around 4.8, performance wise, on Sandy.