I highly recommend getting something with a good cutoff. Running an IQ-X off my hub generator now, the light output is simply astounding. If I put my Planet Bike "2 watt" LED headlight on high, and point it towards the road, I can't even tell it's on because it gets lost in the B&M beam. Even if I point the Planet Bike light level (so it's blinding to oncoming traffic since it has no cutoff unlike the B&M), you STILL cannot see the Planet Bike light because there's not enough above level to reflect off of.

A light with a good cutoff isn't blinding AND provides far more illumination.