Steve, if you'd stop being so argumentative and read the post, I said the DE rivalled the output of a 400w while consuming less power. I hope I don't have to explain why the 250 takes less than a 400
The pendants also direct less heat towards the surface of the water compared to my 400 SE bulbs.
Basically, if you want a good bulb in a clean package with the same end results as 400w for less power consumption, go DE.