My current QGIS installation (2.14) on OS X 10.11 is set up to work with GRASS 6.4.4. I am guessing this is the default GRASS version that comes preinstalled with the QGIS package maintained by William Kyngesburye.
However, I have GRASS 7.0 installed on my system (from Michael Barton's packages), and would like to set my QGIS to work with GRASS 7. In addition, I would like the GRASS plugin for QGIS to use GRASS 7. As you can see in the attached screenshot, the GRASS version the plugin is using is 6.4.4 (2014).
I tried to set the "Custom" installation path to my GRASS 7 installation, but the plugin tells me that particular GRASS installation is not valid.
P.S.: GRASS 7 and QGIS are working fine on my OS X 10.11 installation, as I have disabled SIP.