My impression is the 150 NBT is a bit stouter than the 150 Sierra, but I'd not hesitate to use the Sierra. Can't really see the need for a mono. The 7-08, like the 308, isn't especially tough on projectiles.
I took a decent 6x6 bull with the 150 NBT season before last... bullet traveled 32" of elk at an angle. Quickest kill I've ever seen on a bull.
My first choice would be the 140 Accubond or Partition if you can get either to shoot. Otherwise, I'd not hesitate to stay with the Sierra.
