That doesn't make sense to me, kickback occurs on the compression stroke.

opening the exhaust early wouldn't make as much sense as closing the intake early.

Versey ,I think your looking at the wrong end of the compression stroke ,the exhaust valve lift is reduced by .010 ,that means the valve overlap is reduced and the exhaust valve both opens and CLOSES sooner which might lower the chance of the fuel igniting in the exhaust pipe and burning back through the cylinder making the piston move backward at shutdown.

And if the piston stops short of TDC ? bad things happen ! AS I stated earlier the exhaust valve with less lift closes earlier LESSONING the chance of the piston being pushed backward , not that it still can't happen.

OK Versy , I thought the kick back occurred when the piston approached ,but stopped short of TDC on the  compression stroke.

Unless someone can show me that the duration spec on the exhaust lobe is also different(258 according to the diagram), I don't see how the lift would change opening or closing times.  My theory is that, for what ever reason, Suzuki was trying to keep cylinder pressure longer, or extend the time it takes to do so.  Of course, no one has shown different specs for the two part numbers, and this is all speculation.

It is my believe that the event that can break the starter gear and case on early bikes occurs when there is a strong explosion after you shut of the ignition.

I believe that there are 2 potential causes of the explosion:
1)  As the engine is coasting to a stop and the fuel/air is being pushed into the exhaust....it can be ignited.  If this explosion occurs as the engine is on the exhaust stoke....the valve is open and the pressure can potentially push the piston down and cause the engine to rotate backwards.
2)  It is also possible that when the ignition is turned off and the engine is coasting down to a stop.....that the engine loses momentum right after an intake stroke as the piston is on the compression stroke.  If there is almost enough momentum to take the piston very near to TDC without actually crossing over....the fuel/air mixture will be compressed and ready for ignition - and I believe it is possible that the hot engine could ignite the fuel/air without a spark.  NOTE - while I acknowledge the chances of this are somewhat remote....I do believe it is possible and could happen - and it is more apt to happen when a bike is really hot or running really lean.

Both of the above situations are not common - most times the afterfire in the muffler occurs a second or two after the engine has come to a stop....however if the exhaust valve is open the fire and pressure in the exhaust could go into the cylinder and push the piston down.  I also believe on rare occasions it is possible for the fuel mixture to ignite in a hot engine on an "incomplete" compression stroke.  Maybe?    

Great discussion ad very informative!