I like the idea of dynamo hubs and dedicated lights and have been running such a setup for years.

Initially, I was worried about weight and drag, but the additional weight on a commuter bike is not a big deal and the drag is nothing I ever noticed.

I am running a Shimano dyno-hub with Supernova E3 Asymmetrical headlight and E3 tail light. The light I'm using looks like it is out of production, replaced by the E3 Pro 2. I thought mine was rated at 350 lumen, but the new one is marketed at 205. Huh. In any case, it is a focused-beam with German-law-spec shaped beam made to cut glare to oncoming road users. The rear is very bright but since it is German, steady-on, which I supplement with a blinky rear light on my helmet.

Mine are always on, daytime running lights. No hard data at all, but consider this an anecdotal thumbs up for feeling like they do add something to daytime conspicuity and resulting safety.

I also have a rechargeable 700 lumen headlight which I can swap between any of my other bikes which are not equipped with dynohub and dedicated headlight setup. Between the two, I really love the dedicated setup for not having to worry about recharging or misplacing the rechargeable light, but I also like the swap-ability of the rechargeables. On my dedicated commuter, it makes a lot of sense to have gone with the dyno setup; with today's LED and rechargeable battery tech, I could easily go with a rechargeable system and not look back.