I think the most important thing you can do for yourself is to ask yourself about the kind of video you're doing and how serious of video equipment you need.
My day job is working in commercial video, and we use a pair of C200s on every shoot, aided by EOS Rs and 5D Mark IVs, mainly on gimbals. If you're shooting long interviews, work with complicated audio set-ups, and need ND filters outdoors, absolutely nothing beats a cinema camera. Some of the documentaries I've helped film we've been in situations where we needed to just hit record and leave the C200S rolling nonstop for like four hours straight. Beyond that, hour long interviews are a piece of cake when you're working with the cinema cameras. One boom mic with a long XLR straight into the A camera, shotgun orlav mic for second track, it's tough to beat the functionality and professionalism that a cinema camera brings to a shoot. On top of that, the built-in ND filters are probably one of my most used cinema camera features, and it makes getting F/1.4 outside in daylight a breeze, especially when you're running and gunning and go from inside and outside often. All it takes to switch between 0 ND, 2-stops, 4 stops, 6 stops, 8 stops, is a push of a dedicated button in either direction, and when your exposure changes you always have the option to instantly hit the ND filter to correct for it without changing any other shooting parameters or fumbling on set with lens mounted NDs. The Cinema batteries are also killer, the BP-A60 battery lets you shoot for *so* much longer than my personal R5 does.
We're actually considering soon picking up a C70 to compliment our C200s, mainly for the size/weight savings we would have for being a bit more nimble, all while it maintains the same connectivity with two mini-XLR inputs, full-size HDMI, BP-A batteries, built-in ND, etc. The C70 actually has better quality than the C200 thanks to the new dual-gain C300 Mark III sensor, other than not having raw video, so it's likely the C70 will be our primary A camera. On top of that, we're very interested in the C70's speedbooster giving us some room to have a more full-frame look in some situations, though that's not a deciding factor as super 35 has never felt limiting on the C200s.
The flipside of all of this, is that outside of my day job, I work for a newspaper as a photojournalist using my own R5 and 1DX mark II. I don't do nearly as much or as intense of video for the paper, so in that scenario I have no issue using the R5 and 1DX2. I love my R5 and have absolutely no complaints about it as a stills camera, but if I used it for much paid video work I would definitely miss so many of the features that the C70 and C200 offer.
I can understand your conundrum, though. When the newspaper has me shooting a video of a graduation as well as a gallery of 50 photos, it's a hassle having to juggle cameras to handle both video and photo on the same shoot. Normally, in those assignments, I've used one camera on a tripod just shooting video, and shot photos with another camera. One video perk for the R5 is that when you hit the record button in stills mode, it switches to a custom video mode of your design, which I have set to shutter priority at 1/60th to ensure the proper shutterspeed for video, and switches back to your stills mode when you finish recording. That's nice when I'm on scene of a fire and have to shoot photographs at 1/1000th but also can hit the record button and immediately be at 1/60th recording smooth video when something happens.
I ultimately shoot maybe one video a month at most with my personal equipment, so I could never justify having the kind of equipment I have at my day job, but I've long considered picking up something like a C100 to dedicate to being an A-camera in those instances. I'm very interested by the rumors of a C50 as an RF mount C100 at a price point under the R5, which I think would be an ideal fit for me.
