I think that of the two types of FWD, the most common is the fixed bottom bracket like the Cobrabikes or Zox uses. They don't turn as well at low speeds, but they don't have the pedal steer issues at higher speeds. Like the trike cornering issue, I'm not sure you can put a number on where FWD will start losing traction. It will depend on the weight distribution of the particular bike/rider combination.