Just watched Australian professional bird photographer Jan Wegener's YT video comparing the R5 and A1 cameras. Very fair video review IMO and thought CR members might enjoy his thoughts on both. I will tell you in advance that the R5 held its own and exceeded in some tests he put both cameras through. The A1 was def better in some regards, of course but look at the price difference between the two bodies. Overall, he found the R5 to be a better hybrid camera while the A1 excelled at FPS and filling up its buffer more slowly. At any rate, here is a link to Jan's video where you can make your own observations and draw your own conclusions. In fairness, I should mention that Jan(pronounced Yaan) is a Canon shooter, using primarily the R5.