We run the same render path for desktop and mobile GL. I have a "proxy" header, which defines functions like gl::Clear, gl::VertexAttribPointer, etc instead. The proxy changes a few function names as needed, and a few things are switched on either compile or runtime flags. (Not many things.) I don't try to fully emulate correct GL ES behavior on desktop; I just want my ES code to run. This proxy does that and works across Windows, Linux, Mac, and iOS.
As for shaders, I found that trying to share them across desktop and mobile was a catastrophe. I now use hlsl2glsl (linked above) with some custom patches for full Mac and ES support. I should remember to assemble those changes into a pull request some day.