Depends on how quickly you want to sample and how slow of a delay you can handle.
If you use for example console.log(currentHeartRate) in the Fitbit Studio it is practically instantaneous. You can monitor in the debugger but you can't remove the data practically. It is like read only unless you copy the log manually with copy and past after you are done. If you want useful live data to extract, you will have more limitations such as the file transfer rate and more steps such as uploading to companion from watch and then uploading to a server which then you can upload to a website with a GUI interface if you want. All that takes time though so you will have some delay. If its any sizeable amount of information it won't be real time as the file transfer is incredibly slow (50-60 min to send 2mb, I think smaller files can maybe get about 10kb/s).
