I have had a brief play with BFD2.2 and am mightily impressed with the dimensions it adds to the Zen. Earlier, I also tried out BFDeco as well and found it to be a very easy entry into the world of VSTs.
I hope to do full user reviews of both of these - as well as the rival Toontrack offerings in future editions of digitalDrummer, but off the bat, I must say that the 50% off should be enough to encourage any doubters out there to have a try. And FXpanssion has some terrific videos which introduce the products and explain them. If you haven't seen the Zendrum ones by Mr Emrich, they are a real eye-opener