When opening the Blend file, uncheck the option "Load UI" in the file browser.
Both variations use shadeless materials so they render pretty fast.
Dark uses Sampled Motion Blur and some basic compositing, so it's a bit slower.
Light: ~20 minutes
Dark: ~25 minutes
Light: ~55 minutes
Dark: ~1 hour
Tested on an Intel Core i5 at 1080p resolution.
Frames: 225 for 25fps, 600 for 60fps
Time: 10 seconds including fade out, around 8 seconds without it.