I recently finished a film at 4K, and I can tell you, I could have definitely used a 6K camera!!!! That is why I am trying to drive home this point.. you might not think you need 6K now, but wait till you actually try to post a film at a clean 4K. Then you will be thanking the heavens for 6K.
In terms of Epic and Dragon, Jim is specifically and explicitly building this camera/sensor combination for 4K finishes. So if people don't care about 4K finishes, don't buy the Epic with the Dragon... it won't be the camera for you. But don't try to bash the camera and sensor, because some of us really, really need it. All of my upcoming projects rely on Dragon.