There are so many lights that work well nowadays.
I used to use a Hope Vision 1 but things have moved on since then. My main lights now are an Exposure Strada and a Fenix BC25. The latter is an absolute bargain. Both are non-dazzle for road use.
I use the Hope Vision 1 on my brompton as a city light. It's a bit Obnoxious in full beam in a city environment. I used to use it for commuting to college on Kent country lanes. I wish Hope would make a modern version that has the same formfactor/battery config, but with more modern optics/LED.
I usually use two lights to give more power for descending and in case one dies (which never happens).
400s and 600s are in summer, with short nights and often with sleep stops, so you won't need really need high power lights for lots of hours.
EDIT. I'd not heard of the Raveman before but just googled it. It looks like a great light. Add one other and you won't have any problems. You don't necessarily need another light of the same quality, a cheap one would do for dawn / dusk and using in urban areas, and save your main light for the dark lanes.
For multiple nights, recharge via a battery pack.
When I was having a crisis of confidence about using a Dynamo for the TCR, I bought a Supernova Mini 2. It's a STVZO approved light, that comes with just a bare wire, you can then plug it into anything from 5v to 21v. They sell a bare wire to USB cable to pair up with it too. You can then run this off what ever USB power pack you have. They make crown mount and handlebar mount etc... It also has a daylight running and auto main beam feature.
https://supernova-lights.com/en/products/e-bike-lights-25kmh/mini-2/I have a 98Wh USB battery pack. At USB voltages the light is pulling about 4W. So in theory that's ~24 hours of use off my USB pack (
https://amzn.to/2G64YZu [1]). I doubt you'd get the full 24hr, but 20hr seems plausible. The power bank has the useful feature that you can charge it from 2 usb sockets (2A per socket), giving you the whole 98 watts charged in 6 hours. Obviously a 500g 98Wh battery pack is somewhat excessive, but a 10000mah (
https://amzn.to/2PxBZ4N) power brick is about 36Wh, so that's 8-9 hours.
I've got a Fenix PD35 (
https://amzn.to/2BVW24V), on an exposure helmet mount (
https://exposurelights.com/helmet-mount). It uses an 18650 battery that is usb chargable. I primarily use it as an extra light when descending, so I can look round corners, when the crown mounted light can't easily be shone in the right direction.
I had a requirement for STVZO approval, hence stumping up for the supernova, if you're not spending a lot of time in Germany, it's probably not a major issue.
The headlight tho has been a real game changer.
HTH
J
[1]Interestingly I discovered that this will also power a macbook, which surprised me. I was at an event at the weekend, and the organiser realised they had forgotten the psu for their macbook, and were worried about it lasting all evening driving the presentations, so she borrowed my battery pack and cable. Worked surprisingly well!