The MOCO preaches that the whine is the result of the straight cut gears in 1'st and 5'th, but anyone with any knowledge of these bikes will realize that in previous 5 speed years, ALL the gears were straight cut and were not as noisy as the new six speeds are.
The 6 speeds have straight and helical cut gears inside. There are other problems with the six speeds being the trap door flexes and plastic bearing retainers also that will show as a chattering (moving) clutch handle under certain conditions. They tried to cheap out on the design and as a result, they ended up with a trans that is not as good as it could be.
Just something else that the customer pays a lot of money to "test" out the new designs that they come out with.