[Lance Bachelder] “I plan on shooting my next feature in 4K – possibly even the new GH4 but will have a better idea after NAB next week.”
Ideally it would be after Atomos comes out with their 4K HDMI recording unit that is heavily rumored to be announced (unless you plan on using the YAGH, but that will require 4 SDI connections to get 4K, which seems a bit much compared to a single HDMI cable).
Internally, 4K on the GH4 is basically just AVCHD.