I always go with 4 blades, and this is why. Inches of "slice". Ok, let's say a deer is 10 inches wide, and you shoot a 2 blade broadhead. That equates to 20 inches of slice, not including the cutting diameter of the head. Now, let's say you are using a 4 blade head on the same deer. Now you have 40 inches of slice. More cut = more blood = dead deer faster and easier to find. Go with 4.