As per the title, currently I have insider pro and what do you guys think of this app? Lumia Battery Saver & Booster - 8.1 | Windows Phone Apps+Games Store (United States)
No kidding. A battery app that needs access to all your contacts (and just about everything else in your phone)!?!?I haven't and I don't think I would either.
The day when MS has a system app that tells you what data on your phone every third party app is accessing is when you know they are serious about your personal data but even Apple doesn't have one yet so I don't expect one for Windows Phone any time soon.
I don't think an app will fix this issue. I understand prior to downloading apps you can go to the section to see what info the app needs access to. Now if somehow the app you suggest can be used as a gate keeper and deny apps access to certain info after installation then I would be all for it. Something like that if possible would be a great privacy tool.