I've done nearly exclusively VR stuff on mobile over the last year, and I use Shaderforge for basically all shaders I build. The general optimization limitations above apply, and there are a few settings in SF itself you should probably toggle: Forward Rendering, "Single Directional" Light count if possible, disable…
@cptSwing, better knobs and options to optimize for mobile are really lacking in Shaderforge. A second pass on the shader code itself is usually common to do some cleanup work. I usually make a copy of the shader in the same directory with a '.' at the beginning so Unity doesn't see it. Then I go through and switch down…
SF doesn't expose precision options for all of it's nodes, so I always go back in and drop them down unless it causes visual anomalies. Haven't run into any problems with it on OpenGLES 3.0+, but got some interesting bugs on some 2.0 devices.