I have been using my magicshine lights (dealextreme) for a few weeks now and I am very happy with them.
They have 5 modes (100%, 50%, 25%, strobe, SOS) and an external lithium battery pack that
lasts about 2.5-3 hours on full power. I only run them 30-45min per day so don't have any
issues with run time.
I think the design requires that they are air cooled as you cycle along since they get very
hot when used off the bike.
can't compare them to any modern high end lights since I don't own any but I used
to have a home made 80w halogen system years ago with a motorcycle style battery.
the lights would run around 45min on full power and the system was over 3kg.
So these LED lights win in usability and don't cost much more.
I also added a RSP astrum light recently since its on sale at a few places.
Cheaper and brighter than the cateye POS that likes to break after a while.
Just bought mine yesterday, isn't two a bit overkill for cycling on the road?