All, quick (noob) question … does the agent have to be windows? I understand not being able to emulate IE but others should work right?
Mostly, yes. The browsers are not “Emulated” - it runs the real browsers and instruments them. Most of the core instrumentation code is Windows-specific.
That said, we’re working on a Node.js agent that can be used with Chrome on any OS: https://sites.google.com/a/webpagetest.org/docs/private-instances/node-js-agent
It’s still missing a fair number of features but the basics should work.