. . . half-dozen of another.
Well, not always. Two days of moderate to dim overcast brought out a number of critter friends, yesterday to face the 200-600mm G lens with 2X. Sharpness on that combo seemed impressive, but color rendering was off. And f/13 generated lots of noise which obliterated details. The 2X will likely be used only with the 100-400mm GM going forward, assuming the zoom can be made to resolve properly.
Interestingly, the R7, with a crop sensor and a diffraction-limited aperture of f/5.1, produced better details and less noise with the RF 100-500mm and RF 1.4X at f/10 this afternoon in similar light, though the shot below (ISO 8000) isn’t a good illustration of that point. Although I can’t seen any degradation of image quality when the extender is added, my default deployment of the Canon setup is without it—for reasons that stand out, literally.
Looks as though the R7 is the #1 critter-chaser at this point. For me anyway, it works well with the RF zooms, better than my experience with the R5. No, APS-C is not dead, not in my arsenal.