I researched a bit of continuous light devices recently as I am planning to do some product shots within a year or two.

The first thing I learned is that taking pictures of people is quite different from taking pictures of objects. Objects don't move, people either move or is more authentic-spontaneous if they actually move.

Flash lighting is better for people because it freezes movement. Flash lighting requires experience or more "proofs" to understand how the shadows fall, what the final effect will be.

Continuous light allows to have a better immediate perception of how shadows fall. Human eye "sees" differently than camera, but you get a closer and more immediate understanding of the final effect with continuous light as you can "see" the light "as it happens".

There basically are three cathegories of continuous lighting: incandescent (variant: halogen), fluorescent, and LEDs.

From what I gather: incandescent are what they say, incandescent, as in "bloody hot". They can even explode. You risk some fire as well if you are not careful. They require a lot of electricity, which doesn't come cheap those days. But you can have any sort of light including "hard" light.

Fluorescent have two problems: one is that normally the spectrum does not at all resemble sunlight. This can be overcome by using lamps with a CRI > 90 (the higher the better, and the more expensive).
The other problem is that you cannot use, in colour work, fluorescent light with fast shutter speeds even if you had power enough, as explained by this text by Curtis Newport:

http://johnbdigital.com/lenses/fluor...t_lighting.php

So you are stuck with relatively slow times and again this is not the best for people, although it is no problem for objects. They are not hot and this is a great relief, and they don't require a massive amount of energy.

LEDs are the last arrived to the party. For what I saw, the products are still expensive and not powerful.

So for the time being I would stick to flash for people, and I would seriously consider fluorescent light for still life. It seems that you never really get a "hard" light with fluorescent in any case. If you want power, you end up having a "soft" light source.

That's what I gathered, somebody else might know better.