Hello people, have been using fitbit for over a year, but I really consider switching to an S4 since I have an iPhone and Macbook, and I would love to have everything on the same ecosystem. Thing is, fitbit has an app that tracks everything and it makes it so very accurate. I understand that I need to download some third-party apps to sleep on the S4 and see which ones work best for me, but how accurate are the other readings such as steps, calories, heart rate, workloads, etc.? In fact, Fitbit allows you to set the length of your step every step to calculate the steps that go, and combined with height, weight, and heart rate it is estimated that calories are burned, etc. What are those features on Apple Watch? Is there much room for this type of calibration as stride length? Are there any other features that would be better compared to a fitbit? Many questions where I know, thanks a mile for the helpers!