The iOS 10.2.2 release is performing far beyond my expectations. The offline capability is working flawlessly (even during crash simulations). I read that this version only supports using a single basemap in disconnected mode, but I was able to find a work-around allowing at least two basemaps that the user can toggle between. Just add the second ESRI map layer as a layer (not as a basemap) in your AGOL map, turn it on and save the map.
I heard that related table support is coming in a future update, and that capability will meet a huge, unmet need.
Kudos to your developers, and please keep up the great work!
Mark