I see it being a bit different the problem with tune is in a way you are assuming all bards want to use instruments, and I kind of see that at the moment there are two possible customization streams for bards.

But say for instance it was:
- Perfect Pitch (For Instruments)
- Dancer (For non instruments)

Both relatively cheap.

Well this could work. But this kind of breaks what is being asked more than one. Further to this the other issue is you kind of make people choose what they are going to do instrument wise so the edge is applied. Which eliminates potential for someone to have a valid reason that they cannot use instruments anymore.