Configuring IE's proxy settings via GPP

I am trying to apply proxy settings to our IEs 8, 9, 10 and 11 via Group Policy and found that "Automatically Detect Settings" option in the Group Policy Preferences (GPP) for IE8 and 9 is greyed out for some reason (IE10 is OK). The PC where I edit the GPP is Windows 8.1 and our domain controllers are Windows Server 2008 R2.

I know it is possible to use Registry preferences as described here however I am worried this registry setting might not be compatible with all IEs versions including future versions. I just can't believe the GPP is unable to configure this simple setting for the IE8 browser..