I've been going back and forth on getting an external recorder for my GH4 vs buying a new camera. Wisdom says get rent a few cameras or recorders and decide that way. For me and the way I work, I'd rather buy an external recorder because I hate the process of buying a camera. I'd rather rig what I have to the fullest. Blackmagic's 5 inch Video Assist seems to fit the bill for me nicely. I can capture in 4k and downsample to 1080p during production, plus 10 bit 4:2:2 ProRes is where I want to go.