Question: for last couple days I read and watch all the stuff about R1 - and realistically - can someone provide any serious reason to upgrade or buy R1 over R3.
The only major upgrades over R3 I found are:
1. pre-release burst
2. slightly higher ISO
3. slightly faster continuous shooting
4. allegedly better EyeAF
Or am I missing something? If someone is OK with how R3 works is there really anything else that justify almost 40% higher price?
I understand that for uber-pro photogs in very specific environments these paper thin differences might be day and nigh - although I'm already pretty OK with 15 to 20 FPS and 16000 ISO on 99% stadiums in Europe (but maybe I'm not pro enough) - but for the majority is there anything else that might be a reason to go for R1?
To be honest, at this point, after almost 15 years with Canon I am starting to think if I would still recommend to someone this system instead of Nikon with its Z9.
Any ideas?
Fair question and comments. A few other features I would point out would be:
1) cross-type AF sensors across the entire frame
2) dual CFE B cards so one can write redundantly to both without buffer limitations
3) brighter, higher resolution, higher magnification EVF
4) deeper buffer than the R3 (1000+ frames in lossless RAW)
5) strap lug on bottom of camera
6) faster sensor readout with electronic shutter so less rolling shutter
7) 6144-devision metering (compared to 384 on R3) for more precise exposure metering even when subject is small in frame. (shared with R5 Mk2)
For me there is not a single reason to upgrade, but it is the combination of all of these features that might make the upgrade worthwhile. Yes, I do wish that Canon would have slightly increased the resolution as well, but 24 MP is okay especially given the fact that I started out with 16 MP back in the day.
The Nikon Z9 is an excellent camera and one that I do use specifically with the Nikon 800 mm f6.3 PF lens. I use the 800 mm focal length for small birds / animals and the Z9+800 mm f6.3 combo is less costly than the Canon RF 800 f5.6.
With that said, both Canon and Nikon cameras have their pluses and minuses; I have yet to find one camera that checks all the boxes. 
