I am still debating this question myself! I realized I can't jump with light jump shafts, so dedicated mainstream jumpers are not for me. I do have both Mezz breakers (PB1 and 2), and while they work fantastic, I am thinking I might be ok with a J/B and save the extra space on my case.
The higher end dedicated jump cues actually tend to be very front heavy as opposed to ultralight. I think it affords more control over speed.