I've only worked with the Red One as well, but after seeing a number of projects shot with the Epic I think that it might be your best choice based on what you say you need. The RED One as you say is fair too bulky for an action film, and the setup time is a little bit longer than what you might find with the Epic or Scarlet. Both the Epic and Scarlet have very easy menus to navigate so learning it shouldn't be a big deal. Both seem to have superior image quality (and the HDRx looks very nice). But, I don't know how any of the RED cameras hold up in an action film so I can't offer any advantages of one or the other in this specific situation. Bottom line, the Epic and Scarlet are smaller/lighter with a slightly shorter setup time and easy to use touch screen menus.
