This is one of the big reasons why a lot of pro photographers haven’t switched to Sony yet. As a Wedding photographer, I really like to have the peace of mind of having a backup of my images just in case an sd card goes bad. I think it’s only a matter of time until Sony begins to implement dual Sd card into their more professional line of cameras.
4. low light autofocus
Coming from the 5d Mark III, I was really accustomed to having really great low light autofocus. When I began using my first full frame Sony camera (A7ii) I couldn’t believe how inconsistent it was focusing in low light. I began to change my shooting style solely aiming for the 'contrasty" edges on my subjects so I could acquire focus. This is improved on the Sony A7rii and A6500 cameras but still isn’t up to par with my old Canon system.