Given to Fly
Marc, agree with what you've said in some cases, but with the high MP it has the makings of a great all-rounder, especially with the multiple formats (3:2, 16:9, 4:3, 1:1) offered. Birders always seem to be able to use more crop.Super high MP is not necessarily a desirable thing. You will see edge blurring from minor shakes unless you have good posture, high shutter speed, or good IBIS. No one really needs more than 24-ish MP unless you want really big enlargements or a lot of cropping. With the d850 (45MP), shot at 1/2500 or faster, I can get 4x-6x crops and still shoot at ISO 2000 - 6400. I'm not sure if a 61MP sensor will be that much better. It's a sqrt() relationship between MP and crop. a 4x crop on 45MP is 2.8MP, on 61MP it is 3.8MP. I don't think that's much difference.
We'll need to see how the AF and dynamic range come out.
Personally, I'm not rushing to order the A7rIV. I'll wait to see what all the Sony announcements are, and what Nikon might offer up in the next 3-4 months. I think the A4rIV is more for landscape & portrait, we'll see what their sports-oriented announcements are.
In APS-C crop mode it will be 26.2MP and offer a 3x bigger buffer - so ~200 compressed RAW, or ~100 uncompressed RAW shots ..... good enough for about 10 seconds of blazing away at 10fps. You also get virtually full AF point coverage across the crop frame. All that, and a pixel shift landscape, or small sized low light /walkaround camera too.
This gives me great hope that the Nikon 'Z8' (my feeling is at least 12 months away - after the Olympics) which would use the same sensor and essentially be the same thing will be the one. I really like the ready info accessibility of a top plate LCD display, so I will wait to see how each of these feel in the hand .... and also what lenses filter through ....
Exciting times for photographers !