Im using two pro v8, It met my budget. Plenty light for night and caves. The angle is just barely wide enough the wide angle im using, so there no wasted light But needing to use two to properly fill the rectangle frame. The two beams knit very well. The light very even. The light head appears to have a regulated power supply which keeps the light output steady, drawing different currents from the battery based on its voltage. Im guessing the head may dim based on measured tempature as suggested by manufacture litature. . They take C but I put AA in them to make the weight right when used on the video housing, reducing total and traveling weight. And im using AA for all the other gadgets brought on the trips, simplifing with one travel charger. I get 2.5 hours from AA Nimh.
Lights using AA (and similar) travel easier, Given led power requirements, compared to halogen, its less weight is more important then the percieved color quality to me. At least finally