If a page is in draft, it is not published and not visible to the public.
Our “Domain Replace” plugin doesn’t transfer site. You should use it after transferring. For example, you have transferred from “http://www.your-domain.com/testing/” to “http://www.your-domain.com/”, now all your post images and other contents will still look in old url because those urls are already set in database. With domain replace, you can update all those in just one click.
If you don’t want your site to be inaccessible, then either you have to make copies of your pages for testing, or I’m afraid, you have to go for a staging site.
As you keep forgetting, we think many others can think in the same way. We are taking your suggestion seriously and will try to update our emails to remind everytime.
Have a nice day.