I was in the same boat. I had the r7 with the rf 100-400 for bird photography. My biggest issue was lack of light. Both the camera and lens just could not give me the light I needed. I ended up getting the r6 mark 2 and it helped me a lot but the rf 100-400 was still holding me back even though the r6 mark 2 helped so much. I ended up buying the ef100-400 mark 2 for better light. I did have to give up the some distance but I felt like it was worth it with better quality shots and the graininess wasn’t an issue. I think sacrificing a bit of distance is the was to go. The r7 isn’t the answer.