Originally Posted by vanttila

Directed at the OP, who said he knows "nothing" on the topic: From a quick googling I found that most dynohubs today draw 3 watts. If the OP pedals at 80 watts avg. during his summer trip, that's a bit under 4% of his power that goes into the light. That's not major, but worth noting. In addition, dynohubs weigh 1lbs and up, though the weight is at the center of the wheel, which lessens the power wasted in this (the rotational energy for a heavy wheel is higher, and it's all wasted when breaking, so lighter wheels are better). In addition, setting up a dynohub requires building a wheel around it (or buying one that comes with a wheel, I suppose), which may or may not be a problem depending on the OP's skills and budget. Dynohubs alone cost $100+.
Once you have the dyno set up, it's true that you have one less thing to worry about, and you "won't have to remove your light every other day to charge." Still, I'd recommend investing in a quality flashlight, handlebar mount, and a battery charger, with a couple of spare batteries. Buy them online from dinodirect, t mart, or another such place and you can get the whole deal for <$25. I ride home in the dark 5 times a week and only need to change the battery once a month if that.