Fitbit's official company blog, with product announcements, API news, and activity and sleep data from its users.
HN commenters cite it for the 10,000-step goal, shipping delays, sleep tracking accuracy, and what data Fitbit shares, rather than judging the blog itself.
Disclosure: #FitbitEmployee but I don't speak for Fitbit.
Any Fitbit with heart rate will give you maximum acccuracy according to https://www.wareable.com/fitbit/fitbit-sleep-tracking-defining-feature-6496
Heart rate is key to getting good sleep stages data, so a non-wearable won't do. https://blog.fitbit.com/heart-rate-during-sleep-stages/
To integrate with Apple HealthKit you need a 3rd party app.
A list of information shared would go a long way. Assuming it's a short list (hah), it wouldn't be hard to prominently display it aside from the privacy policy.
Edit: Also, turn ALL of this into a single step, and make it easier to find: https://blog.fitbit.com/go-incognito/
Fitbit promotes the 10,000 step number. They have a blog post with links to sources. http://blog.fitbit.com/?p=194
Having several family members with fit bits, I can tell you it's definitely do-able. It adds up more quickly than you think!
Fitbit had a shipping delay of about a year. Check their blog: http://blog.fitbit.com/
Granted, their preorder was free.