I just got mine on Saturday. I haven't had a chance to use it yet, but can't wait. I also bought my first set of rulers.
According to my dealer who was trained by Bernina and actually helped write the original Presser Foot Book Series, plus trains other dealers, were smart to wait and buy the Bernina foot as it has a spring on it made especially for Bernina's. The generic foot that some people buy eventually will break parts on the Bernina machines. I don't remember the part, but she did say it was expensive to replace.