Advantages versus graphite:
1. much resistant to degradation by radiation (less potential energy release under annealing) and much less likely to release radiation into the atmoshpere (fire etc).
2. much higher strength
3. lower & isotropic coefficient of thermal expansion
4. isotropic thermal conductivity
5. slightly higher heat capacity
6. automatically very low boron content

Disadvantages:
1. Currently more expensive, but the price could come down a lot if better industrial processes are invented and/or the price of energy comes down.
2. Need more material to moderate the reaction (~2.3x the mass?)