I was bitten by a similar problem one of the very first versions of the FB app, and I haven't tried it again. It synced my Google Contacts (what I use as my can

I was bitten by a similar problem one of the very first versions of the FB app, and I haven't tried it again. It synced my Google Contacts (what I use as my canonical contacts list) with Facebook, resulting in duplicates and a whole bunch of mess that still isn't completely resolved years later. Now that I'm on Marshmallow, I might risk it, but I'm very hesitant to do so.