From personal experience with the Typhoon, I can back up dribbe's comments. After handling the plane during the build for a friend of mine, giving the plane it's first test flight and watching my friend plow the plane into the field several times including cart wheels I can give you assurances that Z-Foam is 'tuff 'nuff. It is definitely stiffer than EPP but I can't say for sure whether it's stronger but I'd certainly bet that it's as strong. The only damage to my friend's Typhoon after his less than stellar performances is a broken cowl, a battery pack holder and canopy clip anchor that need to be reseated and a plastic wing tab that needs to be re-glued. Yep, they were hard crashes but the Z-Foam has absolutely no damage, just plastic parts breaking or coming loose.