"I don't want to be negative here, however it would be obvious that a lens that cost$4000 would outperform a lens that cost $1500 ? BTW,I own the ZF 100 and use it on my D3x."
You are not always paying for quality. Sometimes you pay for a name/heritage, which leica has in spades.
My $2400 D700 out performs many cameras that cost 3x more.
With the leica I feel you are paying a lot for the "Made in Germany" label. Just my two cents... although in a logical world you would be right.
Lazer cut diamonds are free of defects and have better cuts, yet hand ground diamonds fetch much higher prices.
Hand woven quilts etc etc, wonderful thought, but more often then not incorrect.
(Note: I once owned a Hassy 120mm "CB" lens that outperformed my coworkers "CFE" [highest end model] lens but since it was their "CB" [entry level] glass it cost me 1/4 the price)