It's better to have an in-body image stabilization mechanism and double slots for recording media, but I don't think it's particularly inconvenient if you don't have it. Since manual exposure and ISO auto are my basic style of photography, I can get by without image stabilization in the first place. All I have to do is set the shutter speed that won't shake, set the aperture value that gives me the depth of field I want, and shoot with ISO auto. Specifically, if I'm shooting outdoors during the day, I shoot at F8 and 1/500 seconds, so I have almost no worries about camera shake, and F8 is just right for the depth of field. When shooting indoors, I shoot at about 1/100 seconds, so I sometimes worry about camera shake. However, I don't have to worry because the image stabilization mechanism is on the lens side. The latest mirrorless cameras have a specification of 7 or 8 effective stops with coordinated correction on the body and lens, but it doesn't matter if there was no shake during 1 second of handheld shooting. If you want to shoot in 1 second, you can use a tripod, and nowadays there are no subjects that require slow shutter speeds of less than 1 second. If I had to say, it would be fireworks, but that is completely in the world of tripod photography. As for the double slot of the recording media, this is also not necessary for the current shooting style. When I was working, I used to shoot in double slots, one in JPEG and the other in RAW, but now I shoot in RAW+JPEG with a single slot recording media. The number of shots I take is significantly less than when I was working, so I don't feel the need for a double slot. Therefore, I don't feel any inconvenience with the Canon EOS RP and Nikon Z fc, and I don't feel the need for in-body image stabilization or a double slot. In other words, the equipment you use should be decided based on your shooting style. If you are shooting fast moving objects, the Canon EOS R7 would be good, or you would need a more expensive flagship model. However, for people who only shoot occasionally in the neighborhood park, in-body image stabilization or a double slot is not necessary.

JPEG straight out of the camera. Photographed in July 2017. The ISO is increased to prevent camera shake at the super telephoto side. I decided to narrow the aperture to some extent and raise the ISO sensitivity to capture the entire flower sharply. I don't usually take a tripod with me on walks, so one of the reasons I raised the ISO sensitivity was that I was shooting handheld. At this time, I had not yet started shooting at F8 and 1/500 seconds. Canon EOS 7D Mark II, Tamron 16-300mm F3.5-6.3, aperture F8, aperture priority AE, AWB, ISO 800.