Helicopter question

Because of a helicopters blade having to come forward as it spins, the forward going blades speed is added to the forward speed of the helicopter. The result is it seems that 250mph is about as fast as they can go. The tip speed of course is the greatest. For that reason it seems to me that the smaller the blade with lesser tip speed should make the copter faster.

Now to my question. Why isnt a design like the Karmen Huskey used more? With twin rotors, they can be smaller. Also if the greater blade angle is not over the body of the copter, there would be less down wash so the copter would be more efficient. I know that two blades gear together in more complicated, but with two smaller blades, it would seem that it could be faster.

Where is my logic wrong here if it is?