I agree with Gabe. Keying Red footage has never been a problem for me.
Yeah, this is really the only downside. I don't need it, but a Red Rocket would be nice in some workflows.
I've considered building a hackintosh, but the thought of it going down and only me supporting it has always stopped me. Bought a maxed out 5k iMac and I've been very happy.
I think you're missing the point. 6k gave them a lot of wiggle room in post. Being able to reframe shots is a huge advantage. I'm sure the vfx team loved the extra resolution too. The film looked amazing too. Saying it would've been richer with an Alexa is a slap to the face to the whole crew. Cameras don't make the film.