[2]: http://www.narutobase.net/manga/Naruto/550/12
[3]: http://www.narutobase.net/manga/Naruto/461/10
I wondered this as well.
Why would Tobi even want Shisui's eye, if it's a tech that he can't even use multiple times? The Hashi-charka/dna would drastically reduce the time it would take for...