Depends. Brightness isn't an issue. The bad thing about LED lamps is the lack of good angled visibility.
That's my primary problem with my Able2 Sho-Me LED Strobes. In order to get good coverage, you really need at least one strobe on each side plus front and back.
When I repaint my rig, I will end up adding a single white LED cluster to each side of the rack to aid in visibility.
With my current LED strobe setup, I get excellent front/rear coverage. So much so that I get about 1/2 mile daylight coverage and at least 1 mile at night. Able2 says I'm supposed to get 1/4 mile daylight coverage, and with the lights improperly aimed, that would be the case.
Which brings up the issue with the Dominator - if you're going to use it, put it up higher. The placement you're looking to use is good for secondary lighting, but if you're wanting it to be the primary warning setup, it's gotta be higher up.
Here's an example of what I've done to my rig. The cool part of the Able2 stuff - it's so low profile that it's able to literally blend in with the roof rack and it still gives good to excellent primary warning. The Dominator sticks out a bit more, and I'd hate to break a TIR3 light cluster where you want to place it. Those TIR3 units are expensive.
http://www.azhog.org/sho-me_LED_stro...ED_strobes.htm
Movies are available to show an example of daylight use along with other various shots.
-Steve