Great ending for Nina! She went through a lot, and in the end a lot went through her. ;-)
Love how she is still alive when the pole comes out, those are some amazing pictures in the end. And the other two girls can witness it, and after seeing what happened to Mia and Nina, Julieta should be pretty worried for her future, she seems like a girl who would have realistic expectations now.

I definitely prefer male torturers. But I don't mind female torturers, and I really like to see things mixed up occasionally, as long as the victim is a girl. Not that you aren't already doing that in many ways, but showing a girl torture another girl would be something new and interesting. Especially if she's getting forced to do it, but having a female sadist on the team would also be interesting - though if a girl actually switches sides and gets out of getting tortured, there will most likely still be at least one of us complaining who has her as his favorite. ;-)