I own a Polar F6 heart rate monitor which I really like and have recommended it to others. It allows you to enter various information personal to you such as your age, weight,
resting heart rate (can't remember what else) and using that information and your
workout session, tells you how many calories you burned and the percentage of those calories that were fat. I pay less attention to that information than to the average and highest heart rate readings it gives me, and the time I spent within a heart rate training zone (for example, 160-170 bpm).
I have noticed that the total calories burned per my heart rate monitor is a heck of alot less than what the treadmill unit reads. This doesn't bother me as, like I said, I am more interested in my average and highest HR readings.
I personally believe you can't go wrong with a good heart rate monitor. They are your silent coach. Being analytical, like me, I think you'd like the information a heart rate monitor would provide you, and that by using it smartly, you'd take your superfitness to the next level.