Yes, Canon makes decisions customers don't understand. But you seem to be lumping their first production model of mirrorless with ultra mission-critical bodies such as the 1DX...Canon might well be releasing a nuclear-strike hardened body in 2020 (and I'm hoping a 5D type of mirrorless in 2021).
Since when did successful wedding photographers feel compelled to switch from 1DX bodies to mirrorless? And why does it frustrate you that Canon is not following your schedule? Is your business going to be threatened because you haven't switched to mirrorless? I'd sincerely care to hear your reasoning regarding this point.
Yes, a dual-slot pro body will be welcomed when it arrives, but why, in the meantime, are you seemingly continuing to be fascinated by the EOS R? Have you tried it?
And, please, tell us how many times you have had cards fail over how many years? And how many full and happy cards between failures?
Again, it comes down to the benefits of using the R and its lenses against the risk of a card failure at the worst possible moment. Your decision. Sorry I can't get too worked up about the issue at this point, though if it happened to me, I'd be right with you.
"But you seem to be lumping their first production model of mirrorless with ultra mission-critical bodies such as the 1DX." It is not his first production model of mirrorless. They have a lot of experience with mirrorless. In fact, they are Nº 1 seller of mirrorless in Japan (before Eos R). And, I am not talking about "ultra mission-critical bodies as the 1DX". 5D Mark IV have 2 card slots. Canon 90D record in 4K without crop.
"Since when did successful wedding photographers feel compelled to switch from 1DX bodies to mirrorless?" Who said nothing about that?? I have a 5D Mark IV and I am happy with it. But new RF lenses are obviously better in sharpness and performance with low light. That´s interesting to me.
"And why does it frustrate you that Canon is not following your schedule?" Stupid question. Nothing to answer.
Is your business going to be threatened because you haven't switched to mirrorless? I think I did not say nothing about that. ¿?
And yes, I tried Canon Eos R. Good camera. Similar to 5D Mark IV in a lot of things. Better in low light. Not better in other things like burst. What´s the point of your question?
Nothing more to comment to you. I express myself because maybe someone could give me any idea about why Canon is doing some things. Instead of answer me, you tried to attack me with absurd questions. If you feel happy doing that, good for you.
And final thougth, just hope you never have a problem with an SD card in a paid job.