I have a cheap Polar HRM, just tracks your heart rate and allows you to set your target zone, but I was thinking about selling that to a friend and bumping up to the Polar F4 that has a few more features, mostly for the calorie counter. I was just wondering if anyone has had experience with the calorie counters to know if they are fairly accurate? I don't really want to spend the extra $ if the calorie counter is more of a form of entertainment and not truly useful/accurate.

This is the one I was looking at getting if I get a clean bill of health from the Pulmonary specialist on Thursday...
http://www.polarusa..../fseries/f4.asp

I have one. The calorie counter is sweet. As for accuracy I have no idea. For me at least I know it's consistent. If I go on the same bicycle ride for the same amount of time (1hr) at the same speed it's always right around 550 calories. A 20 minute jog is around 220 calories. I assume it's pretty close but my model only begins the calorie counter when your heart rate is over 100bpm

Ya, my friend and I played tennis for about 3hrs and her said we had burned like 530 calories. But she's a fitness nut and in good shape...since I have more to "move around" I probably burned a different amount than her right? Just seems like burning calories would depend on the individual and is a more complicated process. Did you have to enter your height/weight or any other info to set up the calorie counter?