IMHO, I wouldn't waste the time, money or effort on halogen with dynamos. I've seen them--barely. They remind me of old-school (60s and 70s) penlights.
Disagree with you here. I have a 1-watt Planet bike dynamo light and find it quite sufficient for night-time riding. The beam probably doesn't have enough width, but I normally commute with 2 lights these day... failover being a neat feature no matter which light set you own.
Normally, the amount of light you need is a factor of your speed and road conditions. For me, travelling less than 15 mph and actually closer to 12mph, the one-watt by itself gives me enough light to see pot-holes and other obstructions. Coupled with a blinking battery light, I think it gives ample visibility.
And... it's really really nice to know that you don't have to continually futz with a batter charger. I currently have to do this with my DIY light system on my winter bike and it's a PITA...