I have a passive parts Jazz with a Warmoth neck that I ordered to replace the Warmoth P neck that was on it when I got it (and it was relatively cheap back when I first got it). That bass is too darned heavy for me at 10.5 lbs... and I can't stop playing it.
I've honestly been through at least six other Jazz basses through the years thinking that I might find something with more manageable heft along with the same sound and response that has become home-sweet-home for me with this J.
None of the others had Warmoth necks... None of them came close for me. I'm probably going to get one of those two-shoulder straps for that bass just so it doesn't destroy me or else I'll have to consider playing it while I'm sitting down.
For future reference, a roasted maple Warmoth neck with graphite rods and Hipshot ultralites is a light, stiff, very stable, wonderful thing. My Lightest bass ( all Warmoth wood) - a 4 string P, is 6.6 pounds. My heaviest - a 5 string, 2 pickup beast, again all Warmoth wood, comes in at 8.1.