I have two randonneuring bikes with dynamo lighting, but my most recently purchased brevet bike uses battery lighting. On the vast majority of brevets I ride, dynamo lighting offers no practical advantage over the AA battery powered lights I use. On every distance up to 600k I don't need to carry any extra batteries so battery lighting is no more hassle than a dynamo. For longer rides, a B&M tail-light will last a whole 1200k on one set of batteries, and I can easily run an Ixon IQ for 3 nights on 3 sets of batteries, so I need to carry 8 extra AA batteries in my bag if the there is no bag-drop. The Ixon Core is a good backup as it uses the same mount as the IQ and also uses AA batteries. My favorite dynamo headlight is still the Edelux II.