I do not pixel peep, or shoot test images. I understand the desire to have high resolution images. Using the 45 MP on the R5 makes it difficult to revert to a smaller resolution camera. I agree about the bigger file sizes, 45-50 Mb per image and shooting many images.
What really matters is the how good the new Canon sensors are in terms of SNR (SNR < DR as gap between pixel saturation and total noise incl lens is always smaller than the gap between pixel saturation and the noise floor). All images have noise, just not always visible. Noise comes from a variety of sources, photons hitting photo sites at random (shot noise), thermal noise from capacitance gain,...read noise after analog-to-digital gain etc. etc. ad nauseum. Really boring stuff actually! I much prefer when people post photo images here instead of technical charts. We are all aware that our images lose bits of information as we increase ISO levels, especially colour depth info.
Today, we learnt a useful tidbit of information from a post here, namely; Sony engineers lost out to their marketing department, in that they were forced to opt for shallow wells in the new A9 III sensor, so marketing could advertise a global shutter. They did not chose a base ISO, it was thrust upon them, limited by processing horsepower and the max number of photo electrons these shallower wells can store (between read and reset). Fuller wells = higher SNR (not linear, but as a rule of thumb holds true).
Lets hope Canon do not make the same mistake as Sony, and give us a stellar R1 sensor in terms of SNR -> like the R5 did in beating BSI-CMOS sensors in Sony/Nikon cameras at lower ISO levels (albeit with lower colour depth bit info).
We will have to wait for the R5 II later in the year to see what the resolution will be in that camera body. Personally, I do not want more pixels, but lets wait and see what the new tech can deliver.