It is a cool looking tool. I bought one when they first came out and proceeded to shred the sheath on one of my 7/16" static lines. ONly used it one day.
I've followed several threads on rock climbing and rescue pages and most of the people agree, a rope shreader. It can be used but you would need to be VERY careful about setting the teeth.
If you do get one, practice with an old rope.
Tom