I know of several large financial institutions that do all of their performance testing inside the firewall, and thus they own all of their own infrastructure, including dedicated servers that are used solely for load generation. With some of the large load generation requirements (which can be in the hundreds of thousands of vUsers), you can imagine that even a small bump in optimization of a load server could potentially save a company quite a bit of infrastructure costs in the load server hardware alone. Which is why, as part of our best practices, SOASTA advocates calibration of load servers when using CloudTest.