I just received three Sima SL-20LX led lights. This are some very cheap LED lights for use on camcorders. There are no barndoors, no filterholders and you can't dim the light. But they are cheap and weight next to nothing. They work on a internal battery wich seems to last somewhere between 45 and 60 minutes, after that they need a 4 hours charge. That's the main reason i ordered 3.
I charged them and put one on a Canon HV20, locked down the shutter and exposure (no gain) and switched the light on. I also put two on the XHA1 with the aperture wide open, shutter at 1/50 and -3db gain. So, there was some headroom for real low light situations. I then turned the overhead light off and turned on the Sima's. There was only some really small amount of light from a pc-monitor.
The lights are a little on the green side, so i gelled one sima with a '1/4 minus green', wich looked a little red to me. The white balance on the XHA1 was at 4000k, because the lights seems to be in that region, maybe a MWB looks better, i didn't try.
So, no scientologic test, just charging them and turning them on in a room with no lights.
Oh, one more thing. These suckers are bright! Standing in front of these lights did really hurt my eye's.