Lets remember that the current most favored camera in Hollywood right now, the Alexa, is not 4K. Resolution is not the be-all-end-all (unless your making a Netflix Original series -- don't ask). So many other things, like dynamic range, color reproduction, sensor noise, and color science are all more important.
I mean, feel free to get a GH5s if you like. The GH5 is a fine camera, so is the GH4 (I still use mine). I bought a GH5 when it first came out, then sold it after I realized it really didn't do anything my GH4 + my Atomos didn't already do. The 5s should be a nice upgrade, just keep in mind that it lacks some of the key features that even the GH5 has - like intra-frame recording and image stabilization. It's also using a new sensor, so only time will tell how well it produces cinematic looking images. So far, I've only seen a few test shots from it - and to be honest, none of them struck me as looking even as good as the base GH5.
I recently made the move to the Blackmagic Pocket cameras well... Buying 2 of them. I'll still be keeping my GH4 with the vlog and atomos recorder, but the more I shoot with the Blackmagic, the more I love it over the DSLR format.
The GH5s is still going to be recording no more than 11-stops DR, to a highly compressed i-frame codec that is not yet standard... So you'll need to transcode in post. Even once the codec is ready to go in post, i-frame codecs are CPU-resource hogs and will chug along - trying to reconstruct the inter-frames - so you're probably still going to need to transcode to something like DNx or ProRes.
PERSONALLY, If I were you - I'd go with a GH4 with an Atomos Recorder. It does pretty much everything the GH5 does, only you get the advantage of ProRes and DNx Codecs, and an amazing monitor with all kinds of helpful scopes. And it'll cost you a lot less money.
Not to pitch here: But I have a B-Cam GH4 vlog w/ Ninja Flame I'll sell ya if you decide to go that route. It's in great shape.
Edited by Landon D. Parks, 05 February 2018 - 09:12 AM.