I totally disagree - a helmet mounted light will point where you need it - when you need it.

If this thread about using a single light at speeds over 20mph - then there is little choice but a head/helmet mounting. The same amount of power on a handlebar mount will never "reach around" the corner of a road or spot the dog running out from the yard. Any experienced rider will tell you that there are plenty of reasons a helmet light is more beneficial.

I just returned from an all night right and needed my helmet light to find gravel on the corners of two-lane back roads. The light also saved me from hitting a skunk last week.