> We’re taking a new approach by loading the site-under-test inside of a VM in the cloud rather than rely on a locally installed browser extension.

So while you do get the benefit of clean, repeatable tests, this requirement also puts you out of reach for most enterprise-y applications, where your pre-production environments (i.e., what you actually want to run your tests against) exist in a tightly locked down network environment that you can't reach from the outside. In stricter environments, even a reverse port forwarding setup to allow you to reach inside the LAN would be out of the question.

I think this is a problem you're going to run into pretty soon if you want to do enterprise sales, and one that is not trivial to solve without an open-source flavor of the test runner (e.g. like Selenium).