Yes for sure, with regards to picture exposure, you would need to be ready in advance of the total phase. For the 2017 eclipse, I didn't bother taking any photos in the partial phase. I simply used the lens with solar filter as a means to view the eclipse. I had the camera preset for the total phase, which involved using exposure bracketing. I set up the bracketing for 7 shots with 1-stop gap, using a base ISO, aperture, and shutter speed that I got from reference material. I had the drive mode on high speed, and used a remote cable to actuate the shutter. So all I would have to do is make sure the image was still in the middle of the frame, and hold the button down while the 7 shots were taken each time. The bracketing was enough to ensure that I got the prominences (at the low end of the exposure) to the intricate details of the corona (at the high end of the exposure).

I think a potential disadvantage to using a mirrorless camera for the eclipse is that in order to view the partial phase, you would need to have the exposure set for that particular condition. Then you would have to switch rapidly to the new settings for the total phase. With the DSLR, it doesn't matter of course what your settings are --- the viewfinder image will be the same. So if you're like me and don't care for photos of the partial phase, then you can do it as I described. Or, just take photos of the partial phase after totality, so you aren't in a panic to switch.