Here's a possible workaround to the bad situation I described above (you update Living flag and can't push it to sync up). Make some other random change (like a place name). When RM pushes that placename, it also sends the Living Flag update and syncs that and removes that person from the difference list.
Not great, but not stuck and afraid to make changes at either end. I can probably blast through all my updates over the course of a couple hours, although this would be much better if I could do a bunch of updates at one end and then do a "sync" that does all the same corrections.
It's like when you configure a file sync. You can click a couple rules that say do them all this way (like if I changed a bunch of place names, I could just push them all at once with one click by enabling the rule called "update ancestry changes to match RM if they're different. Don't add or delete anything".
RM seems to be morphing into a tool with several different identities and use models. I think long term, this could fill the gap where the online programs don't offer the full capabilities that a standalone PC has (because of computing demands?). I was able to do custom searches across my whole database that are impossible on ancestry. I can also push my data to free sites (via GEDCOM) to share with non-ancestry folks. Maybe it would help to have a FAQ page at some point for the different use models. Those that want their primary data collection at one place or another, and how to best setup each of these environments. Just a thought. With all these capabilities, using it will be too complicated for some classes of users.