Thanks very much for your replies. I read about some properties of ebony here:
http://www.jthomasdavis.com/ws3.html
I do understand that ebony has a long history in musical instrument construction, it's just that since I will be ordering something to use in a custom bass, I might as well try to get all the info I can on the materials involved. I don't even know if Warmoth would build a bloodwood/bloodwood neck. I was thinking that using 1 kind of wood would be the most stable, even in a laminated neck, and the bloodwood has a Janka harness rating very close to ebony. In any case, perhaps the next step is to just call them and ask.