Before you get too excited, they are only useful on totally deserted roads because they are so powerful. When they are switched on, you can only just tell if the headlights are on or off, that's how bright they are. Good or bad thing depending on how you want to use them.
I did a fair bit of research and went with a pair of spots. They work like a high beam and are best at throwing a lot of light down the road. I used them when riding in the alps at night and on unlit country roads here in the UK and that's the environment in which they really shine.
Easy to fit. I mounted them on my crash bars. Had them on for about 2yrs now and been 100% reliable.