As usual the thread has drifted away from the real problem.
PBEs that are suspect at the very least.
When I arrived in the pit the initial SEP my course attended was a real eye opener in a number of ways.
All the previous companies I have flown for used the DRAGA smoke hood system.
The O2 generator is at the bottom of the apron style front heat shield, this keeps the heat from the generator away from the user's head and neck, plus the whole thing is well balanced.
I have always thought our current PBE is more ticking a box rather than a serious piece of kit. However, its not my train set!