I have the older version. Basically we got one as soon as it became available in Europe.I was thinking of getting one. Do you have the Mio Alpha 1 or 2? Can you have the display on time, with the HRM running in the background and peeping when you go outside the limits? Some of the amazon reviews seem to suggest that when you change to time display, the HRM turns off. How often does it need recharging? My pulse goes from 54 to 120 when I stand up from sitting, so it would be a good reminder for getting into better habits when I stand up, go upstairs etc.
I think it has to stay on the heart rate display if you want it to beep. Though you can hit a button to show the time for a few seconds without leaving heart rate mode.
It can last the whole day on one charge, and recharges quite quickly - around 30 minutes.