I made drivers for several of my golfing friends, using both the 3400 and 3410 heads. I found the 3410 to be the better of the two. While both are excellent heads, the 3410 seems to be easier to hit, both long and straight. Its deeper shafting depth also seems to be more desirable. I believe its wider, front to rear dimension, is the reason for its superior hitability.
Pros: Quality, Durability, Easy to Use, Good Value