I running B&M IQ CYO lights. (One is older, one is newer with that newfangled zone closer to the bike. Can't remember which is which because the names have too many letters. ) Compared to any incandescent light they are a real eye-opener, unless you look into them in which case they are a real eye-closer.

I'd add just one thing to RF's description. The B&M lights apparently contain a PIC or similar chip to reduce the light output slightly when the input voltage drops. After all, when you stop you don'pt need to see so much but you still need to be seen. I'd guess it is done with PWM. The effect is to increase the length of time the stand-light operates.