Opinion only
This is just my opinion, but I have played 45 years:
I currently have a J&J Break/Jump, and like it. For the money, it has the biggest bang, IMO. I would only graduate to an X2-Breaker or possibly a Varney (Still favor the X-Breaker more because of tips used by each, and I do a lot of research on products)
A good friend of mine and adversary used to have a J&J Break/Jump cue, and he broke and jumped with it REAL GOOD. That's where I first learned about them. He was making about 85-90% of his jump shots (middle of the table or not). He sold it, and later picked up one of the new Bunjee Break/Jump cues. You can get a J&J from Chrisonline for $60.
He doesn't break as well, a lessor break than the J&J, and he now only makes about 20% of the jump shots he attempts. Plus the wrap on it has come undone, and is unraveling. It has a price of 179.95.
I have broken with a Predator BK, but not with the BK2. I was not impressed with the BK, and unless the BK2 has had SIGNIFICANT improvements, it would not impress me either. I used to have seperate Jump cue from Break cue, and the J&J, I now have, convinced me otherwise. But, with X-Breaker coming out with a seperate Jump cue now, leaves me with more questions in my mind.
Plus, you use less case space with a B/J cue, or incase you want to carry
2 different jump cues (long jumping with accuracy vs. short jumping).
X-Breaker, and the new ones out with X2-tip are the HARDEST
tips out to date, and the X-Breaker website shows a hardness table of different tips. Harder tips are better for breaking and jumping. Plus the X-Breaker tips retain chalk better than phenolic tips, and therefore offer better control.
Just my opinions, and no affiliation.