What does this mean for anyone with Stark Drive that was backed with greater then a 250W motor? Quite simply, it means that as long as you have not modified Stark Drive in any way, and depending on your local countries regulations (if they differe with this EU Standard) you are now able to use your bike legally in your location no matter where you are in the EU.
E-bikes mostly use motors and battery options from a few major suppliers: Bosch, Yamaha, Shimano, and Brose. A few other brands exist, but are less reliable or powerful. Some, like the Yamaha system, have more torque and others are quieter. But generally all four make good options. Look for motor output (in watts) which will give you an idea of total power. But watt hours (Wh) is perhaps a better figure to use—it takes into account battery output and life to give a truer reflection of power.