I always work with Chrome in combination with Mendix. (+) = Chrome is faster. (-) = you can get some styling issues. For example: the Mendix Form POP-UP functionality can give you problems. When the POP-UP is opening there can be some resizing issues. You can fix this issues with your CSS / theme.
We used Google chrome frame in combination with IE. Adding a line in the theming html activates the Google chrome frame. And you need to install the plugin. We had some issues with the upload/download widget and reinstalled it. Don't know if that issue is solved.