so what your experience now with the R3 vs R5?
I sold my R5 soon after I decided I want to keep the R3. The eye control works reliably for me. The 30 fps and the slightly advanced tracking capabilities were good enough reasons for me to upgrade. For me, the R5 was slightly smaller but the R3 is much larger. I wish there was an in-between option in terms of size and weight but there is none
The only cons for me with the R3 are weight and price. I am not sure the price gap between R5 and R3 is totally justified. I would have liked a 36MP instead of 24MP just so I could have the liberty to crop without worrying about losing detail. I've got the Topaz s/w to up-res it for me if needed..

I could operate the R5 with my 28-70 with one hand but the R3 definitely requires both hands.
Here's an image of some goose I shot recently with the R3 and 100-500. If I didn't have a Sony a1 also, I may not have upgraded to the R3 perhaps.. I do need the ability to crop!
Have not shot any motorsports or events yet.. but will return to that later this year!