After reading all this why didn't anyone think of Ironwood??? It clearly states that iron wood can be used on Bows.
"Greenwood can be altered or enhanced with wood-shaping magic such as ironwood, shape wood, and warp wood." If you can have a greenwood bow than you can have an ironwood bow.
If that is the case, then you can have a +1 Composite Ironwood Long Bow (+x). Unless someone can show me RAW that disproves this it stands that any bow can be ironwood. this would make sense to use with the Empty Quiver style feat for any archery based character so you only have to carry one weapon at all times and never have to worry about destroying your bow while bouncing it off a troll's head.