Ok I drilled down a bit and looks like you are right, although I'm still not sure I've built up a clear understanding! (https://physics.stackexchange.com/questions/187917/thought-e...). In fact that question (series of onions) is exactly how I visualised it...
I'm not quite sure from that discussion why an event horizon is equivalent to a body moving outwards at the speed of light but it does make some sense. GR is always fun!
I still don't have a good idea of the "slow moving crossing the event horizon" case" but I'll read around it some more
Maybe the difference is between "free fall through an event horizon" vs "hover" (as much as is possible) at an event horizon
I'm not quite sure from that discussion why an event horizon is equivalent to a body moving outwards at the speed of light but it does make some sense. GR is always fun!
I still don't have a good idea of the "slow moving crossing the event horizon" case" but I'll read around it some more
Maybe the difference is between "free fall through an event horizon" vs "hover" (as much as is possible) at an event horizon