Can you name prices for the three shock mounts (Neumann-made original, plus two alternatives)?
I often find that if a mic owner of a name-brand product sticks with OEM accessories, the package is worth more when it comes time to sell.
But if the Neumann shockmount is exorbitantly more expensive than the copy design model "A", the equation changes. In any event, I would not veer away from the standard-issue cage mount type, unless the alternative is substantially cheaper, which, in the case of "B" as you wrote, it is not.
Regarding functionality: Neumann's cage mounts are a happy compromise between shock absorption and low internal (i.e. elastic string) resonance. I am not familiar with the two alternatives in this regard.