I will tell you this upfront......go for the 2018 with Future Shock. Di2 is pretty awesome, but from a comfort standpoint, not that significant to be the deciding factor.......you'll also be getting the older Di2 that mounts externally.

The FS will put more miles on the bike, compared to Di2.

I'm 5'5" and the 52cm fits really well. Which dealer are you working with? There's only a handful in the area?