While video at night can be deceptive, here's some good ones:

Planet bike compared to Radbot 1000
http://www.youtube.com/watch?v=fxnYHRINovU

Here's a Blackburn Mars 4 vs a Dinotte 400R (the 300R is about 25% less bright)
http://www.youtube.com/watch?v=ElnMZNOH2mg

What is notable is that most of these little AAA or AA rear taillights are not particularly useful. A car coming up on you at night is just not going to identify you as a bike they just see a little blinky light. THe bigger uber powerful taillights are going to cause them to slow down and go wide around you. It's a huge difference in safety. The Dinotte 300R is a super bright (300 lumens) tail light that is self contained.

The Radbot 1000 is just starting to get into the range of usability, IMO. I'd get several of them. The Light and Motion vis180 is next but all of them are small time compared to any of the Dinotte tail lights.

J