I've been working through AP on the 2017 iPad Pro 12.9 running 10.3.2 as well for the last 5 days and have experienced the same freeze/crash scenario, especially when working with masking and more than 3 layers. I've narrowed down some of the issue to an apparent memory leak when allocating a new layer- using a third party utility to force release of formally unallocated RAM seems to dramatically reduce the frequency of freezes.
I highly recommend the official docs emphasize the horsepower and RAM required for AP to do its job, and strongly suggest to users to close all other apps whilst it's running.
It would also be extremely helpful to offer a temp restore file, and offer to restore the work-in-progress to the last known valid state before the crash. It's frustrating to expend 20 minutes on a new project, and lose all of it to an unexpected goodbye kiss.
Hope this is of some value (as an Apple Dev myself, if I may assist in any way with alpha/beta testing, please feel free to PM as time permits)-
Regards and Congrats on a great start!