As of now, Live Sync is enabled for main->{environment} by default for models and content.
It would be great to have the ability to turn this off by default; that is, a main environment would not push to child environments AND there would be no linking that would occur given the models and content are not pushed.
This is valuable because we like to have very selective control over what gets merged back into our other environments; similar to a Git workflow. It also reduces issues with duplicate content getting created.
A bonus feature here would be the ability to turn of live sync for content of a given model; For example, if I had an "Blog Post Page" model, it would be nice to be able to turn off live sync for all content entries in that model, so that newly created Blog Post entries in the Main environment do not automatically show up in the other environments as well.