I race an r6. There's no difference at all between a 600cc and a 1000cc bike off the line assuming a capable rider. When I launch, I can't keep the front wheel on the ground at full throttle, until about 70mph. Yes, if we are talking rolling on the throttle, not using any technique etc the big torquey twin will win Everytime.

Once you are in third though displacement takes the lead, and my smaller engine bike is at a disadvantage!