Maybe I'm just slow today, but I don't get how placing them outboard reduces the risk. If the rotor gives, the engine gives, and it doesn't matter if the FADEC is hit. Putting the FADEC inboard might even reduce the energy of the shrapnel a little bit. Now, the oil tank, I would prefer to put outside the plane of rotation just for the fire hazard it represents.
I think (if I understand tdracer right) this particular risk analysis is for debris from one engine impacting the other engine - if it has enough energy to go through the engine and take out the FADEC then both engines are toast anyway, but if it only has enough energy to get to the inboard side and do a little damage, it might be better if it didn't hit the FADEC. But not, in the end, better enough to justify building left and right engines.