The scrapiwashi, looks lighter and consequently gives a better feeling of balance. However, perhaps its too light. I was looking at the scrapiwashi you-tube video. It seems that the scrapiwashi had difficulty in cutting through a 2x4 . The first section where the young lady is making cuts in a 2x4 .She is not making too much progress.They never show her totally cutting through the 2x4. This could be because she was not using proper technique. Looks like random swing cuts. However, I am sure with a little training she should be able to cut through the 2x4. The next sequence shows the young man attempting to cut through the 2x4. It appears that he is exerting a lot of power in his cuts with very little wood chipping. In this demonstration he still does not cut all the way through the 2x4. Check time sequence 1.28 in the video. It looks like he cut all the way through. However, if you look closely, he just knocks the 2x4 over instead of cutting completely through it on his last swing. I am not saying anything bad about the scrapiwashi. But perhaps if the sword had a little more weight. The cuts would have been deeper and he could of cut all the way through the 2x4. That being said. There is definite advantages in a lighter weight sword for anti-personal use. It would be faster and more "lively" in the hand if you were attacking "soft'' targets. But for me. I would feel more comfortable if I new that my sword could also completely take out "hard" targets (dismemberment of hands, arms and legs). After all .If you take away your opponents hands or arms and even if he is on PCP .There isn't too much that he can do to you after that. This is just my observation and opinion. I am no expert in "Iai".