Even not using encoding or HDD caching, the Z is a better option.
Initial build you do not need to install the video card - Makes troubleshooting easier if by chance have a problem.
If Need be, problem down stream can remove GPUs and still use computer.
Just make sure the MB has video out on backpanel (some gigabyte MBs do NOT).
I have the Astock Z68 Extreme 4 and it works fine. Myself I'm a gigabyte fan, BUT when Z68 boards first came out none of the Gigabyte Boards had Hdmi out on the back panel - Their Rational, If you are going to buy a i5-2500k and a higher end MB you WILL be using a GPU and not the IGP.
Okey I guess it does no hurt having an IGP...
Then the Astock Z68 Extreme 4 does everything I need. But it's pretty much the same as the GA-Z68XP-UD3R.
So maybe it's still better to take the gigabyte as it's the same price?