I picked up set B and the surprising thing was that it relaxed my knee position by being slightly lower just enough to alleviate cramping I would get at times.
The install was straight forward other than I would recommend that you carefully remove and re-install the piece with the spring in an up/down movement and/or tape it down before removing it. It took 2 hours and tons of swear words to put that spring back in.
Good so far 
