I think the hex core 3930k for 500 is well worth it, it will beat the 990x, even if it's slightly, and it is 500 dollars cheaper..
The problem is this mobo, it's only dedicated to Sandy E, which sucks, so I can't upgrade in the future.
For now.. If Intel makes an Ivy Bridge E it should use the same socket. Its just a 22nm shrink with different transistors (tri-gate).