Not sure if this has been suggested yet or isn't viable, but would it be possible to have HM sync, sync your player notes? I can see this being a problem with existing notes that might be in conflict with one another, but couldn't it work such that it only adds notes where there are no notes at all?
This is a pracitcal feature to have for HM sync, because I believe actual hands and player notes are what people will be looking to keep synced between multiple PCs the most.