In regards to steering assist, I've noticed, if it was active previously, it stays active even if the car slows to almost a stop (way below 30 mph). It will stay on even if crawling in traffic. It then turns off if stopped for more than a couple seconds. It does not appear to reactivate when resuming speed, at least until it reaches past a certain speed and it redetects the lane markings.
I've compared the overall behavior of PP versus a M3 AP, and it does appear the M3 somehow is able to detect very faint lane markings better. But PP is definitely more forgiving when providing steering input and does feel more natural. Either way, if they are able to improve the PP software, that would be great, but I have not read anything indicating they would do so...yet.
2018 SL - In Service 2019 JUN - 2019 OCT 96.7 SOH
2018 SV - In Service 2019 JAN - Location: Raleigh, NC - 2019 OCT 93.7 SOH
2013 SL - In Service 2013 FEB, Sold 2018 JUN (50,050 mi) - 4 Bars Lost (44,255 mi)