[Nonfractal]

Alan uses carbon rear axles, I use titanium ones for disca. Not convinced with carbon for the rear as they twist under torsional load. 

We gave up on carbon rear axle after the first DiSCA car (kesselrun corvette) for the reason you state. 
SlotingPlus titanium for the rear every time
Carbon for the front but be sure to use rounded end set screws to lift the axle. Sharp ended set screws will cut into the axle)
Alan