It'd be cool, but bows should get different ammo than other guns. Because it is so versatile, you should have to buy arrows of different kinds in different quantities.
And as for the switching of the mode, it should be a side button like the katana sheath, not like dual pistols. If it is the same button as the bow, it can be a pain to switch from one mode to another, and it also makes it more difficult and time consuming to reload. I also have this problem with dual pistols, because sometimes I prefer to use only one pistol. And yes, I do reload manually from time to time.