Used to go offroad and one thing we learnt very quickly is that you can only ride to the capabilities of your lights. Offroad downhills with our lights were limited to about 25mph till we got a more powerfull lamp. On the flat and not too bad and as I found out- you can even turn the lights off on the uphill sections to save batteries.

Doesn't matter what light you have- how expensive- how powerfull or how good a reputation it has. Lamps can run out of battery or even fail. I still fit a "Spare" front lamp to the bike when night riding and it can come in usefull towards the end of a long ride. Rear lamps and always fit two. You can't see them and if one falls off or fails- and you only have one- you have no rear lamp.

But by far the best lamp you will ever get is a helmet lamp. May not be legal for road use but invluable for seeing round corners- looking at direction signs or notes and for repairing the bike if necessary.

My main lamp is good- probably too good for the road but it does have a low- medium and high setting. It is a twin 5w luxion LED lamp and LED's are the way to go for on road- providing you get the right type. If you just want to be seen- then one with a flashing mode will work. If you want to see- then get at Least 3w. If talking about the "Old" Halogen- then 10w and you can see well enough but more will be better.