Ditto, but I have too similar already, Powercore II 6700 and two Powercore 10000 and a Powercore Slim 5000. Probably what would make me buy is a dual-socket so it can recharge 2 items at once. Currently I solve that via a 10000 + Mini.
I am thinking if they make 3 21700 cell items it will be wider and room and power for a 2nd socket. Waiting.