They are lighter, which reduces kick and improves cyclic rate of fire, which in turn improves your efficiency by allowing your gun to be run at a lower pressure/dwell.
This is true, but there are better bolts out there. What gun do you have? this will let us find the perfect bolt for you.
edit- Looked in your sig, and you have a wrath. Try to find a all-derlin bolt. The supafly is only half derlin the other half aluminum(i think). So a full derlin bolt should be even more light, efficient and so on.
__________________
I had to change from Wesley's sig and avatar. I was tired of Medic and Doomsydaisy sending me nudes