Hi Adam
Thanks for the reply and advice. Though I’d have thought that it’s only going to be an issue with upcoming versions of OS X; it works with current versions as-is. And who knows how many more versions of OS X Apple’s going to bother with support for this 8-year-old model! I don’t really see why Apple would screw with the EFI to override the NVRAM; after all, other Macs of the same vintage didn’t have a discrete GPU, so it would really have to do it just to mess with the subset of people who have done this mod. Seems unlikely. This isn’t a ‘mission-critical’ Mac, so I’ll worry about it if it actually happens, and roll back to the last working version if they screw it up at some point in the future!
I think the beauty of this mod is that if the NVRAM gets reset by a bios update, or for some other reason, you can always start up in Safe Boot Recovery and reapply the dGPU disable; there’s a section of the guide that shows how to set up a script to do the job for you, to make it easier. OS X updates that update the graphics drivers should no longer matter with R8911 removed.