outlast a z68 chipset yes - agreed - faster than a z68 + cheap Ivybridge ?
not sure - you could almost buy a Z68 + 2500k now, sell the 2500k for 100 when Ivybridge comes out, buy an Ivybridge - and still be around same price as a 2011 + 3820 ?
You can, but Ivybridge is the end of the current Intel cycle with Haswell set to be the begining of a new one, so to upgrade from Ivy will be a new cpu and mobo
SB-E is the begining of Intels enthusiast tick/tock cycle, so you will be buying into the start of a new platform that will see you through Ivybridge-E as well.
It is even better value seing as IB-E has been delayed to 2013, so extending the life of the enthusiast platform