Sony's FS700 has plenty going for it regardless of its 4K potential, not least in terms of its super slow motion shooting up to 240fps at 1080p. Nevertheless, if 4K it has to be, then a new NEX-IFR5 interface unit will be out in June to make full use of the camera's big sensor and 3G-SDI output. A couple of things to bear in mind: in addition to this $2,500 interface, you'll need a recorder like the AXS-R5 (around $6,300 plus extra for cards) to store your weighty 4K rushes on, plus you'll find that shooting in this mode will limit slow-mo to a four-second bust at 120 fps. Read the PR for further detail on using 2K with the IFR5, as that format allows continuous slow-mo and ought to be less brutal on the budget.