We're talking about negligence... not recklessness or an intentional tort which have a higher culpability standard. Not sure what they taught you in your "risk management class"... but an express assumption of the risk (contractual consent)releases a defendant from an obligation of reasonable care. That doesn't mean they don't have any duty at all, but essentially its contracting the typical duty of reasonable care under the general negligence standard. However, as we stated before... this does not preclude liability for negligent maintenance (i.e. negligently maintaining the ski lifts) but does release a defendant from the typical negligence standard.
sorry to sound extra nerdy and shit... but this is the type of crap law school has pounded in my head.