Yes, I posted in that thread, but it didn't really take.
In my opinion Jack as a bad guy had tons of potential and it could have totally changed the dynamic of the show. I can easily imagine that Sloane's redemption could have been very real and he could have turned out to be a good surrogate father of sorts for Sydney - despite their troubled past to say the least.
Also I'm guessing that it was Jack who stabbed Vaughn in the back. There was really no reason to hide the identity of the attacker from us if it truly was Katya Derevko like Vaughn suspected later on.