I have a J&J jump/break cue, got it for Christmas. It's the first break cue I've ever owned, having broken "off the wall" before. Therefore I'm not the best person to ask about differences and such.
What I can tell you about mine is that it is put togther quite well, for such an inexpensive cue. It certainly lets me scatter the table on the break quite well. This is also the first phenolic tip I've ever encountered, another learning experience.
I'm having to adjust how I break a little, since this is vastly different than how I was breaking using a heavy house cue previously. I believe it's for the better, as I'm really focusing on the mechanics of the break-stroke more (I have to!).
I like the cue. I don't know that it will be my last break cue, but for the money I paid ($56, new on eBay) I can't complain. For that price, it's a great value.
(I haven't tried jumping with it, since I haven't learned how to jump properly yet. I have far more pressing things to learn and get better at before attacking that technique. One of my buddies used it to jump a couple of balls, and he seemed to like it, so far as that function goes.)