If you are going to do it either way I would go maple backed Osage as I think the Osage backing could overpower a maple belly. Maple is a good backing wood but usually on lower weight bows up to about 40-45#. Hickory and bamboo are better for higher weights
You'd have to know the numbers for Osage and Maple in tension to establish that Osage would be bad for a Maple belly.
Certainly Maple is good for much higher than 45 pounds. Didn't Marc post a 130 pound recurve with a Maple backing?
My comments are more from my experience than facts - which is how I made it sound there. I haven't done a lot of wood backings and none over 50# but in conversations with other bowyers they seem to favor those two for heavier bows. I have some bamboo I got from Del which I can experiment with soon so I'll report back on that....I can't draw anywhere near 130 though so I can't do a comparison there unfortunately :0) My general (and perhaps limited) understanding is that high tension strength backings can overpower low compression strength bellies so I'd tend to try to avoid combinations like that but yes I do have a lot of experimentation to do yet before I can be more authoritative than that. Not that I'll probably get around to it, I prefer good old rawhide anyway....
