I have been dreaming of a build that will outweigh some of the turn-key mid drives both in terms of speed and range and of course the cost.
Surly Troll or Karate Monkey + Schwalbe Super Moto X tires + 50V, 22Ah triangle pack from em3ev + BBS-02 750w- 48V + Tektro Dorado 203mm rotor w/ cut off hydraulic brakes + gear shift sensor from lectric cycles + Body Float.
Now, if only Paul can release 3200mAh cells!!
It's good idea to hold on, I have heard that Haibike will be releasing some speed pedelecs with bigger battery for 2016 (well, I know nothing about it)