What the heck, i'm bored, taking a break from interminable sunday afternoon session of veneer repairs on wife's 1926 BBC table...:^)
If you mean soft maple/silver maple/ = acer saccharinum or big leaf maple for shafts, I don't actually know, but the wood is a whole lot less dense than Hard/"rock/"sugar" = acer saccharum. Some of the former is almost like poplar density. Not something i'd consider.
However for butt parts, with a good core, soft maples are often more readily available with extreme figure than hard maples. BE, fiddleback, and burls. I have avoided it in the past due to access to highly figured hard maple. However, i have some bigleaf burl that tempts me. Soft maple is about as dense as mahogany or maybe a little better, depending on sources of both. Certainly denser than Koa which some use with cores due to the figure.
smt