I think you've gotten some great responses from others. My answer is always "it depends". Particularly on what you shoot. I live in Colorado with plenty of sunlight and shoot with a 1DX2 and R6. Some of it is wildlife that you cannot approach so large focal length is required.I really appreciate the thoughtful responses
I really appreciate the thoughtful responses you provided. It'm also thinking I should persevere and accept there is a learning curve shooting with the longer focal length. I think I also need to embrace cropping as required and consider upscaling my images if I want to print. Do you think the 100-500 is a reasonable replacement for the EF 70-200 2.8 L? I realize I'll lose the 70-100 focal range but a one loss stop of light seems like a reasonable trade-off. The plan was to sell this older EF lens to partially fund the purchase of the RF 100-500. I'll obviously wait before selling and test but I wonder how you might react to the idea? Popular opinion seems to be that the RF 100-500 is the sharpest and best native option for my R body short of shelling out substantially more cash. II'm sure there's a lot of folks out there that would love to have it and I'm lucky. First world problems...
In the past I used my EF 70-200 f/4 and later f2.8L II quite a bit, partly because they were my longest lenses and I had the EF extenders. As I acquired lenses with greater focal lengths like the EF 100-400 II, they got less use. I still have them and use them when appropriate.
As I build my RF kit, I've settled on the 50, 24-240, 100-400 and 800 for now. I've considered the 24-105 but I'd like to go wider. I'm noping the RF 17-70 would be a good companion for the RF 100-400. Someday I'll pick up another R body. Just waiting to see what gets introduced.
I still use the 1DX2 and fast L glass for serious photography. I also use much of my EF L glass on the R6 (11-24, 24-70, 35, 85, 100 Macro, 135). I'm in no rush to replace these. I haven't used the 70-200 on the R6 - just haven't had the need yet.
So your 70-200 decision really depends on what you shoot and how you intend to shoot it.