No, there isn't a difference. A blackout where
everyone sees a page
with a particular message instead of the article they wanted is
exactly the same as unscheduled downtime where everyone sees a page
with a particular message instead of the article they wanted. If
search engines and caches can survive one of them, they can survive
both, since they are identical from an external perspective.
I'm sorry. but this is silly. I have a hard time believing that you
aren't simply trolling here.
- Ryan