after installing hi/lo hid into my halogen housings i didn't adjust them and it was way brighter and did blind people (lot's of flashing lights back at me). after adjusting them properly i don't blind anymore (haven't been flashed since). the highbeams do need to warm up, but that only takes a mere second or two since they are the same bulb. if you have the seperate hi and lo bulbs then it will take longer.

you will not blind anyone if you take the time to adjust the beams properly after installing them. this doesn't just mean adjusting the height, but also the width of the beam. you should have a vertical and horizontal adjustment.