Cubes are generally built to manage higher speeds that are legal in other countries so motor should be OK, and disc brakes should be able to cope, (after all you will go far faster downhill) but yes there will be much faster draw on battery and higher speeds will lower lifetime for other parts.
Not planning on getting one anytime soon. I have had alot of problems with the bike had a new frame and motor fitted due to bearings going, they couldnt get the motor out so had to replace frame aswell. Seems OK so far but dont want to make warranty void by altering/adding anything.
The bike is the green Cube Reaction Pro Hybrid 500 had it around 6 months.
It was something to do with the bolts being cross threaded by factory on build, they couldnt get them out. Cube replaced the frame and motor under warranty so must have been a genuine reason otherwise I dont think they would have.
PowerPacks are the fuel tanks of pedelecs. State-of-the-art lithium-ion technology makes them into efficient and longlasting suppliers of power. As an eBiker you can ride with them very conomically and thus maximize the range of a rechargeable battery charge.