Order your German dyno products from Germany instead of sending some one else's children to college. When I got my dynamo setup earlier this year the Luxos U was $103 at starbike. bike-discount.de also had good prices.

I opted to separate lights and USB power supply so I'd have multiple failure domains, and wouldn't automatically lose power to my GPS when I turned on my light.

In my case that was a Schmidt Edelux ii for $125 and USB-Werk for $54 from starbike.

The Edelux ii shares optics with the B&M Cyo Premium ($58 at the time), but has a nice shiny silver aluminum case instead of plastic. It's great.

The USB-Werk is great for my Garmin Edge 800 GPS, but doesn't deliver enough current to keep my Samsung Galaxy S5 charged in rolling hills. If I was relying on power hungry devices like that I'd try the E-Werk with external cache battery, or maybe the current Tout Terrain with steerer mounted cache battery (but am still running a 1" steerer tube frame, and haven't even updated from my threaded fork).

I'd avoid a non-integrated cache battery. With the boost from 5V DC to what it takes to charge the battery you can lose 20% of your limited power output.