iPhones are very accurate in the 'Find My Phone' app. The wifi iPad, however, can be off up to half a block, or more, from its actual location. I had my iPad stolen and while it did show a location it was not there. In watching the tracking on my new iPad I have place my iPhone and iPad right next to each other and the iPhone shows right on top of my house right on top of the room in it in. The iPad shows down the block about four houses and across the street.
When submitting a claim through AmEx, they want a 'ton' of documentation and a copy of your insurance declaiation paperwork, police report, copy of your AmEx bill that shows the purchace, copy of sales receipt... the works. They only pay you what they can not collect through either your home insurance or busines insurance.