Several players in the NFL have worn the double layered helmet. That soft outer shell is probably very effective at reducing trauma.
I still think the NHL needs to take ALL of the plastic, fiberglass, composite weave materials worn above waist level, out of the game. I don't think ANY player should be wearing hard armor on any part of their body higher than the "cup", except for a helmet. Shinpads, of course, but elbow and shoulder pads should be closed cell foam or some type of soft rubber. Taking the huge, hard caps off the shoulders and elbows would go a LONG ways to reducing injuries in my opinion. About the only place I'd allow hard cap, is over the heart/sternum.
There are a LOT of fairly easy ways to change the equipment without changing the game, but like I said, players are VERY reluctant to be early adopters.