How much can a hardfoam case endure?
There have been two occasions where my violin could've suffered massive damage: 1) when I left my violin at my house for 8 hrs and when I came back there was deep gash like depression on the side of my case (someone at my house had been reckless -_-). I checked to see if my violin had been damaged (because the impact seemed that great) but it was okay; 2) this one happened half an hour ago when I was moving my case to another location and I bumped it into a chair so bad that even a family member was shook. My violin survived that, too.
Its great and all that my violin has survived but I want to know how much my case can endure.
Your case can endure a lot, but your violin will be always in danger.
It's a $200 hofner student violin. I'm not sure what your definition of a good violin is but mine won't cost me money if it's damaged but rather sentiments.
Foam cases protect from shocks and temperature changes, but absolutely not against crushing. We need a stiff, tough, heat-insulating non-splittable outer shell containing enough foam in the right places to avoid any contact between this shell and any part of the violin under any circumstance.
Once a foam case has been damaged (you mention a gash) the shell will start to fall apart from fatigue and offer less and less protection. You should get a new case.