A strobe will overwhelm the output of either light so the color temp doesn't matter. The warmer light of the halogen makes it easier to see and some feel it works better because of that. I don't agree. The camera needs light to focus properly but it's not important that the light have a distinctive, warm appearance.
The halogen FIX light puts out a lot of light, arguably more than necessary and wider than necessary. It's a luxury to have underwater and is easily the more desirable light to have once shooting. The problem with it is that it uses a proprietary Li-Ion battery and charger, offers shorter burn times and less durable bulbs. If I were to use the halogen version I'd swap out the bulb for the 10W variety and possibly use a narrower reflector. I'd prefer longer burn times than the stock configuration offers. A 10W bulb is more efficient than a 20W bulb dimmed to half output and the 20W is so strong you will frequently be dimming it.
The LED version is not as wide and is adequate in brightness but not generously powerful. It uses AA batteries and offers very long burn times that allow you to leave the light on for a whole dive and still run it all day on a charge. I would prefer even brighter LEDs and less burn time. The light is harder to see with the eye in daylight but the camera likes it all the same. I consider it good but not perfect, just like the halogen version.
I think it comes down to whether you value the durability and AA battery solution of the LED light versus the greater output of the halogen. I use the LED one myself. If cost matters, the LED is less expensive and uses cheaper batteries and chargers that can be shared with strobes.
