I have been using an Anton Bauer Ultralight 2 with a 20W 12v MR16 bulb (I think about 40 degree beam). It's pretty good for shooting news, you can go to a higher wattage MR16 if your battery can hack it. I wouldn't use it for interviews though unless it's for news or a bit of fill. I have a mini softbox that makes it a lot easier on the interview subject and gives a much better image. It uses a D-tap to take power off my A/B batteries but I think you can get a 4pin XLR. I've looked at the new crop of LED lights in their various forms and I'm not quite sold on them yet. They just don't seem to have much punch. Maybe someone can suggest an LED that isn't a joke, because the low power they draw sure is attractive.
Hope this helps.