Andy did a test to see how Eevee would compare to Cycles when rendering a scene from Spring. You can download the file and try it for yourself (Blender Cloud subscription required), but this is not for the faint of heart: the download is 2.2GB.
This is a proof of concept to see if it's possible to get close to the render quality using just the eevee viewport and to help optimizing it for future releases. To achieve this I had to convert most of the assets we had on the production to eevee shaders and bake the rock shaders down to something simpler. Even though most of the set is in this file, the majority is actually hidden to allow for faster renders.
To enjoy eevee, just set viewport shading to 'rendered'. The final render was done with View > Viewport Render Animation. For faster performance just set the property HAIR_PARTICLES in Spring's master bone to 0.
Further, the playback speed leaves a lot to be desired, so maybe someone has some ideas to get it performing faster. Help is much appreciated! :)