A:AnswerThe primary difference is the charge HR is larger and has a heart rate monitor where the alta does is smaller and does not have a heart rate monitor.
A:AnswerI have the Alta, and it recognizes when I am biking. It doesn't show as steps on your device. It will show up on the app as the amount of time you spent riding. I have found it to be very accurate in tracking my time on the bike.
A:AnswerYes, I found the band VERY frustrating when it was very brand new. It seems to be better now, so I highly recommend just working the clasp, off wrist, a lot at the beginning. I have noticed the company is now offering a watch-style clasp, but feel it should be the default for new Altas.
A:AnswerYou may not be able to, but if so you will have to turn in the Charge HR, along with its charger and you will have to re-purchase a warranty for the Alta because the original warranty is only good for one replacement.