The first level I tried was Blowtorch and Corkscrew, since you said it definitely worked there. And it did work, however, I'm not sure if it continues to work once you die. But then again I was at the part that you said was the hardest (with the MG). After being blown up by a random ass grenade that didn't give me a marker/warning I had a ridiculously hard time getting passed that part. But everything before that, seemed extremely easy. If the enemy did hit me, it would do massive damage, but most of the time they would miss or wouldn't shoot at all. But, like I said before, after I died they seemed to always know where I was and always seemed to hit me even if it was virtually impossible.