Thanks for the comments, good feedback throughout. I think your point around the minimal stats, that it risks the focus being on justifying the actions is a good one.
No characters can't die, or leave the game, so injured has limited impact, max injury is not death (I should have pointed that out). That's a simplification around having people sit down and go start to finish in one sitting with no one left behind, so hopefully the GM can make it seem a bit scary and the players finish the game before that start to make things too hollow.
I'm definitely not sure about the pacing and number of successes, it may well be too slow at the end.