Still loving mine, and still learning from it! Slysam, how much lower were your numbers? I'm really surprised to hear that it's lower than your other HRM, especially with all the personalization. As far as net vs. gross, I would think that would only make a huge difference with a longer workout. Right? Or maybe with a shorter? Can't wrap my head around the math.
My Fitbit doesn't record HR at all, of course, and its calorie counts are always much lower than my HRM. From using the HRM during different activities, I'm beginning to see some patterns.
Today I was on the elliptical for 40 minutes doing an iClimb workout. The calorie burn was very similar to my Peak Fit Interval workout earlier this week (10 calorie difference), though both were the same length (10 second difference). I could tell from the graphs that the iClimb was much more steady-state (for me) even though it incorporates intervals of more resistance and faster speeds. What's funny is that I somehow thought I could work out harder on a machine and burn more calories, maybe because I could easily adjust resistance. This iClimb doesn't go that high though, or that fast. And it's probably easier to get on a machine and adjust resistance than to make yourself jump higher.
Maybe the lesson so far is that calorie burn is relatively similar between different activities whether steady-state or more interval-ish. If you're too exhausted for HIIT, steady-state will still do the job if you maintain a slightly heavier level of exertion for about the same amount of time. My average HR for both aerobic workouts was the same.
Of course, I have read that calorie burn AFTER a workout is higher if you do HIIT. I wonder if I could wear my HRM all day and figure that out? I know the Motoactv has to be recording a workout to read HR. Sitting at my desk probably wouldn't count.