-
Pass-through charge is an obligatory feature in my opinion... so you don't have to care about how much charge gps/mobile/power-bank have... just leave it all connected, and only disconnect when you get to a climb that really hurts and don't want to think about the little watts you must be losing with the dynamo dragging.... or when night comes and lights should get all the dynamo power. A switch for those two moments would be awesome :), but disconnecting/connecting a usb cable is not so bad one-handed.
I keep buying Anker batteries. Love them. But they're not waterproof and don't do charge-through. They're smaller than most other options and work really well but perhaps I should look at other options.