Whatever the difference is with 2018.21.9 75bdbc11 vis-a-vis Autosteer and hands-on detection, it is a big step backwards.
I have a September 2016 S 75 (Mobileye) and I use Autopilot for ~55 of the 70 miles on my daily commute. I keep at least 1 hand on the wheel more than 99% of the time and both hands more than 90% of the time. The car occasionally delivers a false positive flashing-around-the-edge warning (i.e., my hands are on the wheel, but maybe I'm on a long straightaway and I'm applying torque evenly on each side of the wheel, so the sensor detects no resistance). It happens maybe twice a month and I consider it "worth it" for all the other benefits of Autupilot. In 21 months of daily use, I can count on 1 hand the number of times I received two warnings in a single commute. I have NEVER received the "Autosteer unavailable for the remainder of this drive" message.
Last night I updated to 2018.21.9 75bdc11 and this morning's drive to work was my first commute with it. I changed nothing about my driving style, route, speed, etc. relative to the last ~21 months. I received my first warning just a few miles into the drive (with BOTH HANDS on the wheel) and my second warning ~10 miles later. After ~25 miles, I received my first ever "...remainder of this drive..." message. What gives?!?!?! I am about to get a second Model S but I will strongly reconsider if this is the new normal when it comes to Autopilot. If this continues, I will no longer consider it "worth it" per above.