You are talking about BSM (blind spot monitoring) and yes, the GT/Tech has that. lane departure is when you fall asleep at the wheel and start drifting into the next lane and need the car to wake you up with beeping or shaking.
i like the 16 screen (7"). it is a touchscreen and the nav is new (NAVTEQ vs. '15 unit as TomTom). i personally like the Navteq, but i am starting to think everyone has their own expectations. one issue is that it does NOT have real-time traffic overlay on the map.....you will need to rely on your iphone/android GPS for that. i use the Waze app on my android phone, but i like the Navteq to see the roads better on the bigger screen plus there is no easy way to display/stand your smartphone in the console area without an aftermarket solution.
While true that traffic information isn't overlayed on the map, it seems to be taken into account for route calculation FWIW. We've been doing a lot of trips to Boston and back to visit a sick relative, and last week my girlfriend went a couple of hours ahead of me in her car. When I plugged the destination into the CX-5's nav and looked at the route options, the normal I95/I93 route showed as an estimated 3.5 hrs versus the normal 1.5hrs. Selecting the fastest route took me on a little bit of a detour (a route I wouldn't have even known existed in fact) but sure enough it got me to the hospital shortly after my girlfriend arrived. I appreciated not spending 2 hours stuck in traffic.