To a large extent, I believe the focus on Calories/kilojules expended for any activity session is pointless. Especially if Calories consumed is not tracked. But there are no accurate methods to determine exactly how many Calories we eat either. Nor can we assume that we all digest our food and receive all the Calorie potential in them.

Do you believe that your 85 grams of apple have the same number of Calories as the 85 gram apple I just ate because a chart said an apple provides x amount of Calories?

I wouldn't nix my purchase of a sporting device on Calories if I liked the way it dealt with other features compared to other devices.