I don't want to change the bone roll, that doesn't accomplish anything.
When I have a bone, I want the Y and Z axis to stay the same, but I want the X axis to reflect across the local Y axis. If I try and change the bone roll, it always changes both the Z and X at the same time, even though all I want to do is flip the X axis of the bone in edit mode. "Switch Direction" almost accomplishes this, except then it reverse the head and tail location.
I haven't got a full picture of what you want to accomplish with this but:
What you can do is to have an armature that is scaled to -1 on one axis. That will give you an inverted coordinate system inside that. You could then drive bones on the deforming armature with those bones.
AFAIK bones will end up as matrices that deforms the mesh. Having a negatively scaled matrix on one bone will also scale the deformation accordingly. By using a controlling bone that exist in another coordinate system, this problem will be limited to a non deforming armature, and this is fine.
Blender is pretty inflexible in that regard, it's designed around having the bone's forward vector be Y+ and will mirror by just moving the bone head and tail resulting in similar rotation on both sides. Even if you tried to do this by hand in Edit Mode via scaling, it really just moves the head and tail in such a way that you cannot flip the bone scale-wise.
In other packages, I personally like the scale technique that mirrors the axes nicely. But ultimately all these decisions should be driven by which Software you'll be using to animate. What you do will have an impact on how the manipulators will behave when you select both sides at the same time and try to modify them.
