Died twice trying to make it to the disc switch. The first time I got cut in half by the hatch that the coffins come from in chapter 5. The I got stuck on the scenery in the room where the gunship blows out the windows in chapter 4 and got killed by the bullets. Finally made it to the save point just before Isaac gets grabbed in the church and decided to save there as I couldn't face restarting again.
Last night I made it to the disc switch first try before dying 3 times on the free fall section in chapter 7. By the time I finally cleared that area it was 1am and I have to be up for work at 6. Made my second save just before the zero g area in chapter 8 as there is no way I want to risk yet another stupid death in free fall.
Gonna try to make it to the end of chapter 12 for my final save tonight.