(sorry for taking so long to answer, but I missed the notification). I believe "auto minus" solution could lead to a downward spiral, like you also mentioned.
Let's imagine a player facing an obstacle of 2, with -2HP. To get a partial success they need:
A) + + on the dice roll >> 3 dice (-2HP) VS -2
B) + + + + on the dice roll >> 5 dice VS -4 (-2HP)
both scenarios allow you to have a minus on a roll (if you have 1 skill point to ignore it) or a blank
I believe it's way harder to get B, and that's why I stayed with the A approach.
Your input is great. And I believe it suits the game perfectly, if you're playing an harder scenario, or a game with less rolls, or a game that allows you plenty of health recovery.
What do you think? Thanks for the discussion.