I too have a lumenator - only a few rides, but seems really good and the company seems to be run by a thoroughly nice chap. The battery is quite big - best to mount in the frame, but run times are massive.
Pair this up with a spotlighty one off of Amazon (mine was marketed as an ultrafire SSC P7!), and you have a perfect combo.
Think of the lumenator on the bars as a sort of terrain-follwing radar, picks up everything with a wide sweep.
Then think of the helmet light as a kind of 'missile lock' - a bit brighter, but very focussed, and pointing exactly where you want it.
This is the ideal set-up IMO.