I researched these a year ago and it was by far the brightest most intense light.
However - trends will be going to interior mounted light bars. Departments will start to gravitate towards these due to limited element exposure, reduced fading on plastics and they are very visible.
Look at the Federal Signal Solaris bar - very cool stuff.
http://www.whelen.com/pb/Automotive/ProductSheets/Lightbars/Edge_Ultra_Freedom_Lightbar.pdf
For more help see-
http://www.elightbars.org
- David