I do like dynamo lights for my daily riders, because I don't need to worry about charge state. I have too many bikes (eight, I think) to equip them all with dynamos and lights. I also want to keep a few of them lightweight. Battery lights can move from bike to bike.

But since you asked about complementing dynamo lights, I did that on my 1971 Raleigh Super Course, for extra safety. It has the dynamo lights, so I might as well use them. And I have the battery lights, so I might as well use them, too. Sometimes my battery headlight runs out before I expect it, because I can't keep track of their charge states, so I'm still good when that happens. And when it's not discharged, I put it in the blinky mode for extra attention, something which dynamo lights don't do because of a silly German law. Well, maybe it's not silly. Some people are sure that blinky lights are too distracting, but I don't agree, and neither do many people. They really do get attention faster.