I actually ran Gnome 3 Shell + extensions. I switched to mate because of the insane memory requirements not being able to work on my Ancient Radeon 9600 with 64 MiB ram. I do have to say, with the right extensions, it works really well.
The thing that existed prior to 3.8 was never called 'classic'. It was called 'fallback mode'. 'Classic Mode' is the new thing in 3.8 that replaces fallback mode. It did not exist prior to 3.8. That is what RHEL 7 is using, *not* 'fallback mode'.