Pertty good.
The HD is particularly good in the traction department as evidenced by it's long term successes on the mile.
The timing of the power pulses is such that it recovers during the dead pause to hook up again and is ready for more power.
UJM multies are almost electric in their nearly constant power application and once they run away, they don't recover as well.
The point of the arrow:
Wrap your tire with a single length of duct tape in the direction of travel and observe the lap seam at the end.
That is to simulate the wrapping method used to apply the various layers of rubber to the tire.
Now sit, look, and think about it.
Remember what forces are acting on it when in hard use.
The front tire will do a higher percentage of the braking and the rear will drive you down the road.
Now decide which direction you want the free end of the tape / lap seam to go and see if the factory is correct.