I am not sure if you want the link of their website:
http://mydivinemistress.com/#/welcome/4534050299
Sadism is about suffering. You pay tribute, you get her a gift, you get tormented (including your wallet), and that's that. You got a real Sadist. If you are a masochist, you will enjoy it. There was a young, blonde, very attractive Domme in Vancouver that's now "retired". She personally told me she demanded tributes, gifts, and $500 for just a session. Even in the session, she did things that client consented to, but least enjoyed. Thus, the point about suffering and real sadism! She loved as she called it "real suffering".
So Savannah and Eva are nothing new. We had Ladies like that in the past. You just gotta be a real giver, a real masochist to enter play with those 'dangerous' women, because they are not gonna do things the way you want. Most kinky men, in my opinion, are not suited for something like that. Most are drawn to more caring, sensual Dommes.
I know I am playing devil's advocate here.

I am not justifying 'sadism' but simply pointing out that it is nothing new, and it may not be for everyone.