I'll add this from a very long time repairing, and building basses. I've played and owned a lot of basses as well. Wood, even the same sized billets, varies in terms of weight, density, and grain orientation. String basses, can have either wide, or close grained spruce tops. It's up to the Luthier to choose what will produce the tone they're after in the instrument.
Custom builders offer the same models in many different wood options. What I have come to believe- is not all that much in terms of neck weight will change or improve a bass. It is, neck strength, and RIGIDITY that matters. I built one instrument with a mahogany neck, of simply average strength. It has an ebony fingerboard, and is flexible enough to actually use that to create subtle vibrato effects. It has a VERY strong Martin single acting truss rod in an aluminum 'U' channel. The neck, is super strong. Yes, it's heavier than if I had used a simple threaded rod alone. The bass still sounds incredible, and the big benefit- I have only adjusted the neck once, since 1980 when I built it. I have two other basses with that rod- it is an incredibly strong unit. Remember this- when a factory is building huge numbers of instruments, they simply do not have time, or the need to hand weigh and select the 'cream of the crop' for each bass. That's why they all now have 'custom shops.' I know some players that believe heavier basses sound better. I've never believed that, nor do I think a heavier neck of the same wood species would make much difference, if any at all.