Thanks for correcting my typo (28-70/2 instead of 24-70/2.8) in such a nice way . You are right, the missing 24-28mm range makes quite a substantial difference on the wide angle side. I use such fast standard zooms frequently, too, since many years and models, starting with a manual Sigma 28-70 zoom being my first interchangeable lens, for my Nikon FM-2 (I changed to Canon, when I went digital, and did not regret that yet).Agreed, except personally I’d miss the 24-28mm range not the IS. If the R was my primary camera, I’d be very interested in the RF 24-70/2.8 IS. For my current use of the R (mainly a travel camera), I’ll stick with the 24-105, or perhaps I will pick up the 24-240 when that comes out, depending on image quality.
The EF 24-70/2.8 II remains my most-used lens on the 1D X.