I had the opportunity to test two continuous lighting products, the FotodioX Pro LED-312DS and the Lowel DP D2-10, over the course of two days at the same indoor location. On the first day, I tested the FotodioX during the middle of an overcast day. On the second day, I tested the Lowel and then the FotodioX after sunset.
Here is a reference photo from the first day without any artificial lighting:
I then added the FotodioX from the right without a light modifier:
Finally, I added a diffuser:
On the second day I went directly to the Lowel with a diffusing umbrella:
I then tried the FotodioX with a diffuser at less than full power:
Finally I turned the output of the FotodioX up to full power:
Both lighting systems performed well. The FotodioX is an LED bank that produces a good amount of light for its size and weight. Being able to adjust both the output and the temperature makes it easy to match the ambient light. The Lowel is a halogen bulb that produces quite a bit of light, as well as a non-trivial amount of heat. The FotodioX seems better suited to outdoor portrait photography with its adjustable color temperature, light weight, and battery power. The Lowel seems better suited to studio work, whether still or video, where a panoply of light modifiers (including gels) could give exactly the desired light and a heavy-duty circuit and gaffer's tape could provide the juice.