I tried this, not with comma.ai, but had a VW with lane keeping, adaptive cruise, etc. The first time I did a 6 hour drive with it, it felt like magic. I was essentially on one road the whole time, there was very little traffic, and I didn’t touch the pedals, or really even steer much for 95% of the drive. Just at the start and end when off the expressway.
However, as I made that drive more, it got worse. Traffic was usually heavier, and things didn’t go as well with a lot of traffic. Some of it was how it acted, and some of it were trust issues with it. When traffic picked up or other cars did things around me, I’d switch back to manual control. After a while, I was using manual control the whole time… and then eventually just took the train, because I couldn’t tolerate driving myself anymore.