I have been using this purpose made pulley block on my Swift Light glider for over 200hrs now.
The difference of the force needed to pull the flap rope pulley is a lot less that the standard design.
The problem with the standard pulley block is that the pulley block twists when the flap rope pulley is pulled.
The solution was to design and make a pulley block which is fixed to the airframe with 2 rivets.
With this pulley block the pulley does not twist anymore and the thinner 3mm rope gives a smooth operation.
The amount of effort needed to operate the flaps is reduced, which reduces pilot fatigue.