I have no idea, why this ended up here, but if you are interested in some technical details what SF does: http://blog.stormforger.com/2014/05/27/load-testing-an-inter...
Sounds useful for doing end-to-end from a cloud provider to another cloud provider, but there's more lessons to learn when you have 20 different ISPs and a couple dozen different clients sending you traffic in different ways.
For example, for free services without customer support, usually you don't notice the bugs from all these different devices trying to access your service under load. Once you start charging and provide support, suddenly people are calling you with all kinds of edge cases that affect a minority of users, and you have to invest time in tracking them down or refund the money (which is a bad idea since that builds a reputation that you'd rather dump customers than help them).