I recently had the chance to play with a BlackMagic Design Micro Cinema Camera over at the WPPI show about a week ago. The dynamic range looked better than from the Pocket Cinema Camera, but the addition of 60fps and now powered by Canon LP-E6 batteries is what really sold me. You'll definitely need some type of screen to work with it, but I already own the BlackMagic Design Video Assist (BMVA). Here's a couple of images showing the serial cable connections you can use to control this camera remotely (i.e. Drone use) and also the Camera settings available from the Menu of the new BMMCC.
So if I you're looking to get one ASAP, i'd place your order at DVEStore (here), and then maybe cancel your previous. Their website may still say 'pre-order' but they confirmed their shipment should arrive on Tuesday. I expect these will go fast, and it would suck to have to wait even longer. Hurry and good luck!
Any Sony A7s owner knows there are a few things this camera needs to get the best possible quality out of it. If you want 4K footage, you simply can't record to internal media, so you'll be adapting a recorder like the Atomos Shogun. The battery life is also terrible, so a decent external power option might be the IndiProtools Power Pods (found here).
With these accessories, you'll need a solid way to mount it to the Sony A7s. There's a number of rigs i've shown in the past, and this is just another great option to consider for your A7s. The CAME-TV Sony A7s Cage is available in a variety of bundles if you need extra items such as a Mattebox, Shoulder Pad, Handles, etc.