I look forward to you and others like you to flood the market with 100-400 mkll lenses so you can pick up the 100-500. I still have a great copy of the 100-400 mkl, but the grass is always greener...I don't get all the bashing of Sony fanboys. This is a particularly egregious example when it's quite clear that many long-time Canon users are complaining about the overheating problem. The bashing goes both ways. Sony fanboys criticize Canon users to the same extent--then both sides get into petty arguments about which fanboys are worst. I can't put myself in either camp. I've used Canon DSLRs since 2003 but made a move to Nikon when Canon's innovation slowed. I kept my Canon EF lenses--just too good to get rid of--in hope that Canon would eventually get its act together. I then picked up a Sony a7rIII to continue using that wonderful Canon glass--not surprising, but the Sony's 42MPs gave me the best damn images I ever produced with those lenses. I now have an r5 on order because it looks like Canon has gotten its act together. Lol, Canon has so gotten its act together that it has almost certainly surpassed if not obsoleted the lenses I've retained all these years.
Hence, in addition to the r5, I have the 100-500 on order (I will sell my 100-400) and will likely order the 15-35 after seeing actual r5 reviews. I'll continue using my EF 24-70 mainly because the 15-35 should become my primary lens.
The short of it is, the back and forth between Canon and Sony fans is extremely tiresome. Sony made some great products, and was the source of tremendous innovation for most of the past decade. They pushed the envelope tremendously. Now it looks like Canon is prepared to retake that role. But the r5--just like the Sony cameras-- is not flawless (will there ever be a camera that is?). I suspect that I might lose a touch in DR with the r5 (but not enough to be concerned with), and I'm concerned about whether rolling shutter will be problematic. With my Sony, the files are way too large, there's no articulated LCD, and the IBIS could be a lot better. For me, ergonomics and menus have never been a problem. Again, no camera is perfect.
But my self-esteem is not dependent on being able to brag about my system being better than yours.