Hina is awesome, but IMHO Kallen would kick her ass and rape her with Shirosakura's hilt.
Kallen simply has real battle experience. She killed people before. When Hina is only a HS student. Sure, she gets powered up whenever she uses her sword, or when Hayata needs help, but that doesn't compensate for the lack of real battle exp. And seriously wounding or killing someone is out of the question.
Also, don't say that for the sake of the debate she becomes an emotionless killer, or w/e, cuz that wouldn't be her anymore...