I have a BK2 and Viking BK. I gotta tell you, I break just as hard with my 20oz house cue. I even have the radar reading to prove it. 27mph on my first try, which is the hardest I have ever broke with my other cues. The cue isn't going to make any difference in your break than any other break cue.
The one thing I don't know if I like about the BK2 is that the cueball jumps more than any other cue I have tried. I believe it's because of the low deflection shaft. I bought this cue after trying a BK1 which I liked very much. I think I would rather have the BK1. The BK2 has more of a conical taper to it much like a Z shaft.
IMO the only thing that separates the BK and BK2 from other cues is if you put unintentional sidespin you will still hit where you are aimed at. A cue with high deflection will not be as forgiving.