I don't know about Value in Lighting but effective---Yes.

I bought my light in 2006 when I was offroading. Night time rides as we had to get the rides in and we started off Basic. Two Cateye lamps of 1 watt each and one was a spot and the other a flood. Could be seen in towns with street lights but we could not see well with them and they were no good for offroad. SO- I went for probably the best LED lamp availableat that time in a USE Exposure. Cost £300 and it light up the trail no end. Only problem was that our rides lasted 3 hours and at Max power we had less than 2 hours battery life. Had to use as much on low power so we could still have max power for the downhills or technical bits.

Road riding and I now use that lamp but find it sufficient on low power. That gives about 3watts light and that is what I would suggest as just enough. You can never have too much light when night riding.

Couple of my mates have 3w LED lamps and they are not bad. Cost around £50 ($75) and they have Rechargable L-Ion batteries. Looking around and the price of lamps is going down but 3W is the minimum I would suggest but just as important is the Lens. Some lamps have just a Spot light that will light up the road/Trail 100 yards in front of you but nothing close to the bike.

But one lamp is not enough. They do break down or run out of battery power so a second lamp is always a good idea. Even better if that lamp is a helmet lamp. You can get them in varying power and some of the better ones are more powerfull than My USE. A helmet lamp will get noticed by other road users and is very handy for looking round corners- instead of just lighting up where the bars point--- and ideal for any hands free map reading or bike repairs you may have to make.

But The main thing is that you can only ride within the capability of your lamp. If you have a 1w lamp then you cannot see as far ahead as a 3w so speed will be cut to suit. And a 3w does not compare to a 5w. And as for the latest megabuck street searchlights that are around------------