Aluminum Swingarm

[xpacpal1x_imp]

Honda website says the 2014 CB1100 is equipped with an aluminum swingarm.

Questions:

1) Can anyone confirm that 2013 models have aluminum swingarms?

2) Samurider carries aluminum swingarms mfg. by OVER Racing...it advertises a 50% weight savings from stock. How can this be if both are aluminum? Is the Over Racing hollow and the stock a solid block of aluminum?

3) How many pounds of weight savings is 50% of the stock arm and how significant is that weight, given that its "sprung" weight (is that the correct term).

I am new to motorcycling...simply interested in the variables surrounding this component and not likely to swap into this aftermarket item. Any educated commentary greatly appreciated.