Thanks!
Our infrastructure is all on AWS and designed to scale horizontally, so we're pretty confident we can handle whatever traffic you throw at your app. (Ask about our dedicated-resource hosting plans!)
As for examples, it's a bit Catch-22. Our smaller customers, you haven't heard of; and our largest ones, we can't talk about in public. And a lot of it is internal/intranet stuff anyway.
One customer has kindly allowed us to talk a bit about their app - see https://news.ycombinator.com/item?id=15589020