ProtoFluid simply supports the standards. However, for best results and if the app/site that you're testing is high-end, the latest version of your chosen browser is recommended.
* Although the ProtoFluid app works, the license activation system doesn't.
This is due to licensing requiring CORS support. As soon as this is implemented, these browsers will be fully supported.
ProtoFluid pushes browsers. It is assumed that this is fine due a majority web developer/designer audience.