Hi Pillboy,
Now, Im not AGAINST HRMs, but in my experience you don't really need them.
I use the Rate of Percieved Exertion (RPE) test with clients. If for example the client is cycling, I will ask him / her to give me a score between 1 - 10 on how maximally they think they are pushing themselves.
1 would be very very light, 10 would be maximum speed, and wouldn't be be able to go for longer than 10-15 seconds.
Now the funny thing about this test is that several research studies have shown that a persons RPE score is almost always equivelant to their heart rate, within 5-10 BPM.
So, if someone says they feel they are working at 6/10, this will often mean that they are working at 60% of their maximum heart rate.
As for the calorie counting, I honestly think there is no point whatsoever in doing so. Even though is based on the whole calories in vs calorie out model, thats not really the way your body works with exercise. When you exercise at a certain pace, your body will raise its metabolism and you will burn more calories AFTER the workout.
No form of exercise really burns that many calories. It is the repair of your body afterwards that causes the body to use up calories. So the number you would be recording is usually too insignificant to be worth measuring.
The best way to measure your exercise progress is to set definitive goals based on the exercise you are doing.
If you are using a cycle, you may set a goal of cycling a distance of X km in under X minutes.
If lifting weights you would want to get X amount of reps with a certain weight, then move to the next weight up and set new targets.
But like I said, Im not against the use of HRMs at all costs, I just find them non-essential, and I work with plenty of clients with heart conditions and have never had any problems without one. If you have different reasons for wanting the HRM however, by all means you may find it useful.
My thoughts on exercise calorie counting however, are that its an outdated concept that has no value to anyone.