I have used the Cycle2Charge converter for about half a year and generally am happy with it. Took like 2 minutes to install (I have it wired to the front light wire and the frame, not the hub directly). I haven't performed any multimeter tests, but works just fine for charging phones and powering my garmin even with the lights on (even though manual instructs to turn them off for charging and thus not use the converter when lights might be required, perhaps it has something to do with the German StVZO regulations?). The only drawback is the lack of a cache battery, even a tiny one to last a minute during traffic light stops, simply because the notifications about charging started/stopped are so annoying on many devices.