When you’re depending on image effects for lighting (e.g. HDR tonemapping) having to use the game view to see your levels is a real pain.
I put together a small hack that activates image effects in the Scene View. Code is here: http://framebunker.com/blog/viewing-image-effects-in-the-scene-view/
Please note that this is literally just a quick hack. It seems to work for us, but YMMW.
Have fun!