Mainly the ability to use the iGPU using Virtu for Quick Sync and if you ever need to use it to troubleshoot a GPU problem (VERY handy). VirtuMVP MAY also improve performance slightly with V-Sync enabled.
Also, less importantly, it's better for an Ivy CPU, should you ever choose to upgrade to one.
Well, this rig is going to be for gaming mostly and I heard ivy CPUs aren't worth it compared to the sandy bridges. Is the z77 really worth the extra 100$? Other than being easier to trouble shoot, and the possible performance boost.