I'm a bang for buck kind of guy though, and I don't see a motherboard giving me tangible gains, and it will certainly cost double that of the decent P67 boards.
x58 did not cost double a p55 board. Sure it was more, and in some cases a lot more, but I do not think it was double. I expect the same price points with x79 and z68.
As for the gains, it depends on the user. In my case the gains are worth the money. when I start looking at what I gain, then it becomes less about core count than it does about total system performance.
z68/LGA1155.........vs.....x79/LGA2011
16 PCIe 2.0 lanes...........32+ PCIe (3.0?) lanes
dual channel RAM...........quad channel RAM
1.5MB/2.0MB L3/core......2.5MB L3/core
2 SATA III ports.............Up to 10 SATA III ports (SAS possible)
IGP..............................No IGP
3.4Ghz Base clock..........3.5Ghz+ Base clock
No BLCK overclock..........Possible BLCK overclock
4 cores max..................6 cores with 8 possible with IB