Atomos has introduced a new 4K Recorder that will open the door wide for 4K. The Shogun is a great recording device but expensive. The new Ninja Assassin by Atomos has stripped away the things that you can do without, like SDI recording, and left you with a great 7 inch monitor that will record 4K to the A7s and the Panasonic GH4. I have heard it’s under 1500 dollars.
/ 4k recorder