Although I don't typically work alot of osage, I do cut alot for staves/tradin. I only have two things I can say about dark osage. One is regarding the "dark red steaks" in osage you'll see, that people 'il say make for good bow wood. I have noticed this is always near the pith of the tree, at least on the osage I cut in ohio. The closer to the pith, that darker and compression strong the wood is, at least it seems for me. This makes me think that, what some people say even about white woods, that under the top rings the wood gets better. But who knows. The other thing I will say, is that I went to kentucky, I think two years ago (I think) and cut some smaller diameter osage up real high in the hills. This stuff was noticeably darker and denser than the more yellow osage I cut here in ohio. Also, it was
horrible to cut. And it has seasoned darker too than the stuff I get, I mean after you scrape away the brown on the surface, the "green" inside is a darker orange, where as the osage I cut here is a bright yellow under the surface even after seasoning for a year or so. I got some scraps I keep around for tip overlays, good and seasoned seeing as they are like an inch long and 1/2" thick/tall or something. The yellower osage, when I hit against something metal sounds like wood with a dull thud, or at most a muddy "tink". The darker osage rings like a bell. I made a guitar saddle one day out of the yellower osage, and it was ok. But I was thinking about using some of that darker osage to make one, see how is sounds!
Anyway, all this has made me a believer in quality differences of osage.