The Canon EOS R system turns 3 and Lensrentals.com gives us a breakdown of its progression

[neuroanatomist]

I don’t think anyone actually *likes* using adaptors, as they add an extra interface with additional electrical connections and also introduce a small degree of play when used with heavy lenses.

I *really like* using an adapter that lets me drop in nice, small CPL and ND filters behind lenses like my TS-E 17 and 11-24, instead of the front filtering options for those lenses that are, respectively, salad plate- and dinner plate-sized.

 

[entoman]

I *really like* using an adapter that lets me drop in nice, small CPL and ND filters behind lenses like my TS-E 17 and 11-24, instead of the front filtering options for those lenses that are, respectively, salad plate- and dinner plate-sized.

With my current lenses I feel happier having a good quality protective filter on the front, but yes, that isn’t really an option for the 2 lenses you describe, so I can fully understand the value of an adaptor with a slot-in rear filter.

I’m not so sure of the value of the adaptor with the control ring though - it must feel a bit odd switching back and forth between adapted EF lenses with the control ring at the rear, and RF lenses with the control ring at the front. I’m sure there are some people who find the control ring adaptor useful, but on my RF lenses I’ve disabled the control ring as I find that there are more than enough customised dials and buttons already for my needs.

Currently I’m using a mix of adapted EF lenses and RF lenses, and I’m likely to continue using some of my EF lenses (e.g. 24mm TS-E, 100mm IS macro, 180mm macro) for several years. Potentially using adaptors can introduce a small amount of play, and increase opportunities for the ingress of moisture, although I haven’t experienced this myself. At one stage however I did have a 1.4x iii extender which introduced some disconcerting play/wobble when used with my 100-400mm Mkii and 300mm F2.8.

 

[dcm]

I don’t think anyone actually *likes* using adaptors, as they add an extra interface with additional electrical connections and also introduce a small degree of play when used with heavy lenses. But having said that, I’ve found that using EF lenses on my R5 poses zero issues, and everything including animal-eye AF works extremely well.

I would say "Some people don't like using adapters". And they are very vocal. I don't have any problem adapting EF lenses to my R or M series cameras when appropriate. I'm in no rush to replace all of my EF glass with RF glass, if ever.

 

[dcm]

This is an excellent and very sensible post. It would be costly to switch and that would make it out of the question. I have three lenses with IS and love it and I agree that IBIS would not be all that necessary. I have thought of a 5DIV and and if I need a body quickly, that would possibly be the wisest and most economical quick fix. Thanks again for your excellent response.

Also a former 6D user that moved to the 1DXII at introduction so I could shoot sports and BIF as well. Both of my 6Ds are still going strong as loaners. Given limited funds, I'd stick with the 6D as long as it was meeting my needs. When it breaks, you can decide your next step and save in the meantime. The 5DIV will be there and the R series will keep improving.

I find R6 is sufficient for my current needs (adapted EF and RF800/RF100-400/RF1.4x) so I'm not rushing off to get an R5 or R3. I can wait to see what other bodies are on the horizon. I will say that I much prefer the R6 to the 6D for my use, even with just EF glass.