If I'm adding an atomos, I'll be just as well with a 5D2, to be fair.
Again, I've already owned and sold a GH4. Not going to back to Panasonic unless I get a proper video camera, like the HVX200 used to be.
Shooting on a Red Epic would certainly be fun, but having seen a Red One in the flesh, I don't see that ever becoming a reality. Not because the cameras Red make aren't great, but they're simply too big. The way I usually go about things is a tiny crew and a shoestring budget. If I get a proper budget and crew, I'll probably have more than one guy on the camera, and then maybe, maybe using a larger camera like that would be an option.
As of now though, small but good is the way to go.
Sam: Battery life is not an issue. I usually bring a dozen to the set anyway, just in case, along with two chargers. No problems there, really. The slow motion isn't that big of a deal either. As I said, I owned a GH4. Didn't even touch the 96FPS. I'd just as well use an iPhone 6, and shoot 240fps for that one shot I'd need it for.
bullet: I actually didn't like the menu interface of the GH4. I found it confusing and not logically built up. I remember looking for frame rates, and then I had to go back and change the hertz of the damn thing, and to enable stuff like that, I also had to set it to NTS or PAL or whatever. It's not a bad camera, by all means, it just didn't work for me. Major setback, money-wise, but no cigar. I waited for a potential ProRes or raw feature, but whilst I was doing that, the camera just gathered dust.
I know I'm probably sounding like a jerk, looking for advice when I'm already settled, but the truth is; I'm not. I'm on the fence, sure, but I still think I might do stills some times, and that's when I'd need to have my own camera instead of borrowing.
Which is why I pretty much need 3 cameras.