That's something Slow and Lex have firmly maintained they'll hold onto, the ability to walk away if Curse goes bad. That's been mentioned, worried about and addressed earlier in this thread, so why are you even bringing it up again?
You missunderstood what I was trying to say. It is important that they have this ability, not that they miss it. Although I would be very careful about this, since Curse from business-point has to try to bind them to curse by any means. It is just to early to say if they succeed with it. I do have trust in slow and honestly even a bit more in the people around slow that they will notice any actions going in that directions.
Also yes, the new launcher from Curse will be Mac/Linux compatible, as long as it isn't you can use the old FTB-launcher.
Also don't confuse the curse-client with the new planned minecraft-launcher. The curse-client has no Mac or Linux support (and honestly most games it supports don't work on Linux and Mac), the new minecraft-launcher however will have support for both systems.