I use Obsidian, the Google handwriting keyboard, Dropbox, and Dropsync Pro. I have to be careful to sync before and after I am done writing on a particular device, but if I am consistent I rarely encounter a problem. I have Dropsync set up to auto-sync once an hour.
Oh, I also override the .obsidian config folder on each device, like so:
Before I started doing that, I got an avalanche of synchronization errors every time.
#dropbox #dropsync sync
P.S. I would not call this a “hack”, but maybe someone will find it helpful.