there is no such thing as a concussion proof helmet. A heavier helmet does not mean that it is more protective. take a look at football, those heavy helmets are practically weapons. Ridell tried to get into the lacrosse helmet production, and they claimed with all of their NFL statistics and technology, they produced a concussion proof helmet. turns out that it wasnt. Lacrosse and football helmets need to differentiate because of the different impact speeds and zones.
I would not use a hockey helmet to play lacrosse in. Hockey helmets are designed for a different types of impact compared to lacrosse. the two sports are played at different speeds and space.