I don't commute, but I had a scary episode during my last double that's made me think twice about night riding. I was on Hwy 128 between Napa Valley and Cardiac - very isolated, rural road and all the traffic on it was big trucks pulling boats coming back from a day on the lake, driving very fast. It was probably 8 pm and quite dark - seemingly moonless as it would through a big valley with very little sky visible, no streetlights, etc.. There were no cyclists around me for a period of about 5 miles, and even though I had ridden this same stretch of road in the dark before, the last time I had done it I had been with someone (Veronica), which makes a huge difference.
I didn't have a single "close call" with those trucks, but I just got all in my head about what if's, and kicking myself for taking such risks, etc. Finally in about 5 miles I found another cyclist (female) to ride with the whole rest of the way - which was a HUGE relief. (Especially when my front primary light burned out while climbing Cardiac!

)
Would your return trip also be in the dark? I find I much prefer riding in morning darkness to evening darkness.