I have only now found this thread, and I wonder whether Ithere have been any recent developments that anyone here has heard about.
I too have spent quite a lot of time in recent months trying to work with some of the available devices. (The money we spend, out of desperation...).
I started with a Fitbit charge, which, when you turn it on, flashes up your heart rate ( not very accurately, as I discovered when I got a chest strap sensor), and the steps you've taken so far.
I now use a Polar A360, more accurate, but with same drawback: there isn't a lot of point in knowing that your HR is way over your threshold just after you do something: HR will rush up if you suddenly do anything different: get out of bed, walk up some stairs, have a bad dream...
But in my case it usually goes down again pretty quickly.
I want to know if it's been over the threshold for, say, 10 minutes - that would alert me to a probable crash later on, and to be careful about that activity.
No device that I have found will do this. I realise that it would need a lot more power than you can get from the battery, but it's hard to believe that some technological genius couldn't solve that.
Fitbit though does have one advantage, in that it gives you a graph on the website, for each whole day, that shows your HR on a timeline, and you could go through your graphs marking your activity for each rise and fall of your HR. But it would be tedious, especially if it's not very accurate, and also it's not easy to print out just the graph (separated from the rest of the web page).
Polar will tell you how far you've walked, calories used etc, after each day. But again, it is after the fact, and we are not trying to work up that kind of achievement ladder. Some days I can walk further, many days not at all.
And anyway, steps are only one measure of energy used.
For a week or so I wore both watches, to get the graphs and the better HR - but I felt like an idiot, and stopped.
I use the polar H7 sensor to take HRV every morning; it is interesting, but I haven't been able to consistently relate the numbers to anything in ME. On the stress monitor ( Sweet Beat app) they do give an alert if stress is high - but that is only one consideration for ME, and it's either on or off - no degrees of stress!
I could go into other things that I can't understand in HRV results; but the point is, these things are designed for Atheletes, and we need the opposite kind of monitoring. ( in the Elite app, which I've given up, the only thing I learnt was that, on some mornings when I felt so crashed and ill that I was desperate, it would say 'Your HRV looks good, you can train harder today'.