This is actually extremely interesting. I need to think about how to implement this, but it's great to know. Any PhD candidate info is a plus, thank you for sharing your knowledge!
I would like to ultimately implement auto-tracking, but this will come as the app improves 
In term of feedback, things like what you like in the app is good. What can really be useful is, if you didn't sign up, is a short line on why not, so that I can improve this aspect. 