I almost bought the A7R iv last night, so very close. But what many have already said is true if I'm honest with myself; I don't need 60MP and once the novelty wears off I'll most likely be left with a far slower workflow (until I build my new computer). The buffer issue was another consideration as I do rattle off shots sometimes. I'm also wondering if all the processing power for the big megapixels could effect the AF somehow? Probably not, but just throwing it out there.
Something about the A7C just wasn't quite sitting well with me. Technically it is almost everything I need, but the EVF and also the lack of physical dials etc is perhaps the issue; I do shoot manual almost all of the time. But, being a grand less than the A7R iv would leave room for more lenses.
Ended up buying an A9. The latest firmware helped tip it. So, now I need to decide on lenses. The Sigma 35mm 1.4 has really been taking my fancy, but even though it's HSM will that heavy glass struggle to keep up with the AF? Any other suggestions would be welcome.