I ran into a bug in the High Fall area that prevented me from continuing - it was once I had dropped the second crate that there was an invisible wall blocking my progress here:
I suspect that this was due to me saving and loading in that room earlier (I was facing out from the alcove in the switch after having dropped one crate when I did so).
No final thoughts yet - I'm planning on restarting from the beginning to see if it'll work for me if I don't save there, but I'm very impressed so far.