Man of Honour
Yeah, it's annoying. I tend to turn my Cree off when approaching riders along the canal as it is pretty bright with no other lights around. No one has ever done the same in return sadly.
Someone needs to invent a cheap light with a high beam switch accessible from your normal riding position.
For all their other faults, my old SolarStorm X2 had a very easily accessible switch. It's a shame I never got round to trying to mod it to make it less blinding for other users (and the multitude of other annoyances of course).
uv has recently got an 800 lumen torch for about £35 from Amazon which seems pretty good on that front. He's had to add a hood to make it less antisocial but it's bright, usb-rechargeable and uses only a single 18650 battery built into the main unit. Battery life seems pretty decent in medium mode too (which is about 400 lumens - and actual lumens - compares favourably with my Lezyne in high).