The unit you are talking about doesn't replace a strobe. It is on only when you turn it on so it does not "fire" like a strobe. I have one and I use it in tandem with the strobe. I have had some good results using it. The picture I posted earlier used the light (SL980). The batteries for the external strobe (SL961) were dead and it did not fire (my fault for not changing them) and all I had was the video light and the internal flash (which is covered by the optic ring from the external flash)on my DC800. So you can use it to light up the subject when close enough.
It takes a lot of light to get all the colors the deeper you get, especially red, and the range for the strobe and the light is not that far +/- 8 ft max with the strobe turned all the way to Max. I think having the light makes a difference and helps bring the colors out.