How do I return the result of Ember.RSVP.all from a function?

The function below needs to return a true or false. Inside the then call at the bottom of the function, I get the value I need from result.isAny('hasOverride') but I don't know how to return this value from the hasRoomUpcharge function. How do I do this? I thought adding return in front of Ember.RSVP.all would do it, but it doesn't work. Please help!

hasRoomUpcharge: function(roomRates, defaultRoomTypeCode){
    var defaultRoomRates = roomRates.findBy('roomTypeCode', defaultRoomTypeCode);
    var nonDefaultRoomRates = roomRates.rejectBy('roomTypeCode', defaultRoomTypeCode);
    var nonDefaultRoomMasters = this.modelFor('propertyPricing').roomTypeMasters.rejectBy('isDefault');

    var promises = [];
    var promise;

        nonDefaultRoomMasters.forEach(function(roomMaster){
            var roomTypeCode = roomMaster.get('roomTypeCode');

             promise = roomMaster.get('roomRateUpcharge').then(function(roomRateUpcharge){
                var currentRoomMasterOnePersonPrice = nonDefaultRoomRates.findBy('roomTypeCode', roomTypeCode).onePersonPrice;
                var defaultRoomMasterOnePersonPrice = defaultRoomRates.onePersonPrice;
                var roomUpcharge = roomRateUpcharge.get('onePersonRateUpcharge');

                if(currentRoomMasterOnePersonPrice != defaultRoomMasterOnePersonPrice + roomUpcharge){
                    return { hasOverride: true };
                }
                else {
                    return { hasOverride: false };
                }
            });

            promises.push(promise);
        });


        return Ember.RSVP.all(promises).then(function(result){
            return result.isAny('hasOverride');
        });
},