I'm not quite sure I agree with the theory of her recognizing that she was in a place where other girls have gone missing. I respectfully disagree for the following reasons,
The John and whoever he was partying with must have hired escorts before. I'd say nearly, if not all girls use a drive for their protection. Never once I have heard of a girl driving herself. Thus, the John's would've known a driver would be coming along. Also, I highly doubt SG would've put all the facts together about being in a place where she knew other girls went missing. Prostitutes, especially outcall girls, typically work independently, and only occasionally have maybe 1 or 2 friends in the biz.
I think whatever happened in that house scared her enough not to trust anyone, including her driver, if in fact witnesses saw her driver and not the SK. Whether it be she knew the people in that house were going to kill her, they tried to make some sort of snuff film, something happened that made her act. And prostitutes are typically very, very aware of their surroundings and usually can spot when something isn't right. But I do not think it is because she put the pieces together concerning the missing girls. I also believe the person who spoke to the neighbor and "You shouldn't have done that" after the neighbor called 911, is either under 24 hour surveillance or will be named a suspect. And I do not believe it was SG's driver. I think it was someone who was thought to be the driver.
Whatever happens, I think putting the final pieces of SG's last night together will be the key, if LE hasn't done so already and are gathering evidence, building a case, watching potential suspects etc.