I'm not sure about the 1/1 left-right tricks. My ram watch shows a decrease in X speed by 1 every time the character turns backwards for a frame. I assume a lot of it is slowing down enough to get good timing for things later on, but other times I'm not sure what it's for (or it's to throw an item while backwards). Hopefully there's clarification and I learn something.
Just one other minor thing. Stimpy's Invention level 3 I think, there's a full stop coming out of the pipe into the brick wall. Looks like speed drops to zero for ~8 frames, plus 8 more getting back up to speed. At first I thought this was so he could still hit the switch, but it seemed to work in my run.
Marooned looks great, since it's probably the biggest improvement over mine. Hopefully the eyeball lag can be mitigated in the future, I couldn't get around it either. He catches an edge falling down to the level exit but I'm pretty sure it's the fastest way down.
Overall I think it looks great, with any issues being minor enough to possibly overlook. Again I don't know if the 1/1 movement does affect the finish time, but I could test it if necessary. It would be a shame to have to change "aims for fastest time" to "sacrifices speed for entertainment" when it's such a small thing.