I'm the proud owner of the Cinq5 and Schmidt Edelux LED Headlight.
I've had my Nomad almost 12 months (one year birthday coming up in about a week, 9000km covered so far.)
I added the Cinq5 about August this year. I had a bit of a unhappy introduction to it as it seemed a bit intermittent and getting worse, however .... last week I bought a new USB cable and all of a sudden I have good and consistent connection and hence success with it.
I use the Cinq5 with my Samsung Galaxy S4. I track all my rides via a GPS tracking app (
http://sportypal.com/Workouts/Details/4122975 ) which is very battery intensive - as any time GPS is used.
I don't do these things scientifically or use super careful measuring, but the green LED lights up around 14km/h and starts charging.
Therefore on flat routes I get good charging the whole time, on hilly routes (which I quite like) I get intermittent charging, however the other day I did a flat, fast 28km and had around 89%, then rode another 38 fast kilometres and got it up to 100%, followed by a slow-ish 20km of slow but steady uphill drag (so small you wouldn't notice in a car) and got home with 95% battery, after 92km and 4h 02m - see link above. If I did this same route without charging as I went, I'm guessing I would have got home with 25 - 35% battery.
Come to think of it, I did this hilly (over 1000m of climbing) ride:
http://sportypal.com/Workouts/Details/4125313 and got home with 100% battery - very impressed I was.
I got caught out once, not being able to work out why it wouldn't work at all - it doesn't work when I use the front Edelux light - I'm not sure if there isn't enough power generated to power both or it is just the way mine is wired up - I'm assuming the former.
As for the cap, if you look closely the Cinq5 does have its own push-in rubber plug to seal off the USB connector. Obviously, I don't use it when it is raining as the metal section of the USB cable sits proud and would get wet.
I have only been using it, with the new USB connector, for the last week, but if it keeps going the way it has for the last seven days, then I give it a definite Recommended. The previous couple of months don't count as I had (what I know now) to be a faulty USB cable and that is no fault of the Cinq5. Although there is one quite important cavet: it is not all good news with my Garmin GPS though .... I think it is a known problem with Garmin GPS products and the Cinq5 - everytime I stop at a red light the Garmin goes into Shut Down Mode and counts down from 5 seconds to 4 to 3 etc until it turns itself off. I have to press on the "X" symbol to tell it not to switch off. If I was riding out in the countryside with no red lights or stop signs to worry about, I could get a charge with the Garmin, but when I used it to ride 28kms into the middle of our capital city (Wellington, NZ) I forgot a few times and had it switch off several times. However for daily rides I have never ever run the Garmin flat so this would only be an issue when on a cycle tour and didn't have mains to charge it overnight.
I still recommend the Cinq5 as the Garmin issue isn't too important for me, although it would be nice if they did play together properly.
Tony
NZ