Nathan Frechen
I'm just going to post this to the list for everyone's info.
Not a randonneur, but I use a generator hub setup all winter long for training/commuting. I have a Shimano DH-3N71 hub, which is the better Shimano hub. The drag when the lights are on is negligible, probably the same as if your tires were 5psi low. I'm running a LED-driven headlight and taillight, both with capacitor driven standlights, so that you have light at stoplights/signs. I'm running a Seculite Plus in the back, and a IQ Fly up front. The standlight on the headlight is brighter than the old-halogen light, so the LED version when powered by the hub is roughly twice as bright as the halogens. If you're getting a new setup, don't even consider a halogen lamp, with all of the new LED technology out there. The new generation of the Fly, called the IQ Cyo, should be out in a month or so, and I'll be moving lights, and getting one of those for the geared bike.
My setup has been literally "set and forget", once setup. The IQ Fly even has a Senso setting which automatically detects the natural light and turns the light on if necessary.
Pricy up front, but you never have to worry if your battery has enough power. Alternatively, if overcast/dusky, you don't have to delay turning it on to save power. This time of year, I commute at 6am/3:30pm and just leave it on for a few months now.
For a comparison of beams: http://www.peterwhitecycles.com/headlights.asp
The IQ Cyo isn't on there yet, but it's supposed to be brighter than the Fly by a decent margin. Also, the E3 triple, also not on there, is supposed to be twice as bright as the E3, which might be a nice setup for night mountain biking.
If anyone has any other questions I didn't answer, feel free to email me.
-Nathan