I want to get a second AW for sleep tracking and alarm only. What would be the best model to get. I was thinking about a S3, but a used S5 is only a few dollars more. Is there a difference in the results I will get?
I have an S2 that has been retired and upgraded to S4 when those were released. I've noticed no difference between S2 and S4 in terms of using 3rd party apps for sleep tracking. My experience says either will get the job done for your use case. The differences are the price, new vs. used, internals and resulting performance of the internals--not necessarily exclusive to sleep tracking.