I'm not familiar with how the polor HRM measures calories, but after looking up some info on their site it would likely not be of interest
I'd be more interested if it would actually read correctly as most devices I've tried are not reliable.
However my gym does not allow cell phones in the exercise or locker areas... so sensors that need a cell phone would be useless if you follow the rules.
Much of my exercise is away from the gym: bike riding, sailing and hiking. I don't record how many times I go to the gym or miles I ride bike. And a good windy day racing sailboats is more fun and effective than doing crunches.
When I do use an optical heart rate monitor (seems to be more accurate with a pacemaker from what I've tried) I try to keep my heart rate in the upper 140's as it has a hard stop at 150bpm. I really can't wait until I get the upgrade and the upper limit will be more like 180.
The only calorie count I get is from cardio machines at the gym which I don't record, but I have not idea how to get the calorie count for all the off machine exercise at the gym or away from the gym.
But with 275 times at the gym in a year, it sound like you have a well scheduled exercise regiment. That should serve you well at staying fit. I sounds like you a doing well at keeping active.