Folks:
When we train Sekiguchi Ryu Batto Jutsu in Japan we wrap our own wara bundles with and without bamboo in the center. We only cut at Shoden and above "there"; and only with practicing the Sekiguchi Ryu kata. We cut goza here in the states unless you live in East Texas where rice is grown. But it sure is fun.
Studying Nakamura Ryu Batto Do, I've watch Nakamura Sensei cut goza using the Nakamura Seitei Toho kata (its on one of his tapes). No doubt they work.
Carl McClafferty