I used a BK2 with a 314 and a Z for a period of time because I preferred the weight and balance. It was only after I bought a weight kit that I went back to my "proper" play cue.
The only annoyance using the BK2 was (i) some people kept asking me why I was playing with a break cue not noticng 314 or Z on the shaft (ii) people asking me if they could break with my cue. In terms of play, it was great.
Not sure about the BK3 but my BK2 with a LD shaft had a weight of 19OZ and balance point about 18.2 inches which made it a very balanced cue