I just talked to Mike at 1Z and this was his reply:
Vinyl-Rubber Care 'Tiefenpfleger' is better suited than Gummi Pflege.
Certain properties in Gummi, like it's anti-freezing agent, may hinder
proper operation.
Also keep in mind that wiper blade manufacturers apply a graphite
powder on
the rubber to reduce friction and extend longevity. Applying a vinyl
rubber
conditioner does not necessarily improve performance or extend the
life.