I had always read that in a worse case scenario it's better to have an under exposed image rather than an over exposed image.
I think with the option of RAW we are spoilt for choice as we can essentially turn what seem to be boring photographs into something quite special.
Attached is an example of what I mean:
Here are two images that I took the other day on my way back from a friends house at 5am (as you do)
The first was exposed for what was "correct" from the metering system in the camera.
The second photo is then the processed version to try and recover some of the details in the highlights but as you can see the area around the sun is just too bright and the detail is not there.
The third photo shows what the photo looked like when I exposed for the sun. The image looks rubbish (IMO) and with JPEG compression it would probably be an instant delete for me.
However, with the option of RAW I was pretty confident that I could up the exposure of the shadows and hopefully get a good image whilst retaining the detail in the suns exposure. The fourth image shows how much detail I was able to recover from what seemed to be black.
I'm buy no means saying that underexposing is better as it seems that quite a few people have said the opposite however, I am saying that for how I use my camera I find that if I underexpose I am confident that the detail is still there. I haven't had as much success with overexposing.
From a video point of view I found today that shooting at ISO 400 to expose correctly a scene created less noise than shooting at ISO 100 to create an under exposed scene where in the shadows I had some awful coloured noise. I had been running the camera for quite a long time before then so the sensor was probably hot.