I also am among those who receive complements (and sometimes rants) over my CygloLite HotShot Pro150.

Praises:

• A woman rolled down her window at a light and told me it's the best light she's ever seen. I told her some people complain it's too bright. She said, "Let them complain. We can see you."
• A police officer did a u-turn and pulled up along side me to ask what my lights were so he could recommend them in a bike safety course he conducts.
• Several other motorists have told me both in daylight and at night that it's the brightest tail light they've seen on a bike.

Rants:

• One person passed me at night in his vehicle and shouted "f-ing light!"
• Every week someone shouts out their window as they pass me at night with the intent of startling me. I think the light is visible from so far back they have lots of opportunity to think of something clever (and unintelligible from my perspective as a rider) to shout as they pass by. It doesn't happen much in daylight, nor when I used to ride with a dimmer light.

Overall, I'd rather be visible. But I do believe if I went any brighter I'd probably hurt people's eyes at night and cause them and myself additional risk of being hit by someone who is confused by the flashing. I do make sure to set the light to a more docile oscillating pulse rather than a hard strobe.

In front I have a L&M Taz 1200. It's as bright as I could ever need. I usually ride with it on its mid-bright setting and even that's plenty.

For those concerned with being seen from all angles, there is the Planet Bike Bottle Blinky, and the BrightSide Amber side light. I have the Bottle Blinky. It mounts beneath the water bottle cage on your downtube, and provides three flash patterns (continuous, gentle oscillation, and random strobe). It uses AAA batteries, and in the strobe mode lasts about 100 hours.

My reason for getting it is that people occasionally pull out of side streets, driveways, or 4-way stops without noticing me despite having my headlight and tail light. The side light just assures that there's something eye-catching regardless of their approach angle. It's not anywhere near as bright as my primary lights, but it is enough to get people's attention, I think.

Anyway, there's really no NEED for a headlight brighter than 900lm, tail light brighter than 150lm, and a quite moderate side-light. More than 150lm in back is getting into the range of causing driver confusion and possible accidents. In front, if you're brighter than a car, or less bright than a car but with a poorly-masked beam, you are blinding oncoming cars, and that's also unsafe.