I will second UltraLight... Though the Battery Pack is ****ty. I really like the Orascoptic Battery pack because it'd digital. The Orascoptic light is more concentrated as well and works better with high mags.
Though, nothing can beat the weight of a UltraLight. I used to own a DFV.. and I felt it was heavy, hot, and had a fat cable that never stayed where I wanted it.