Both of you need to read my post again. For sake of time and sanity I am not going to explain to you that 4fps does not compensate for long lag time between the shots and enable capture something at the very exact moment you want.
I spent 3 hours shooting street the first night I got my M. Capturing the moment I wanted just involved pre-focusing and holding the shutter half way until the moment came. No different from capturing the moment with an all manual camera. If you're focused there's hardly any release lag.
You might miss a true surprise moment due to AF. But then again, you will with most cameras. I had one such moment that night (a kid running by me) and I would have needed my 7D to nail it.
I do wish Canon would make this easier on us with some additional options. Let me AF off the record button. And touch to focus (instead of touch to shoot). Make manual focusing useful (peaking + much shorter throw). And give me a DoF distance scale on screen. Give us that and the "moment" argument is completely moot.
Even without that, you can work with the camera and be ready.
1) Your kid doing something cute which you want to capture almost instantly.
I'm not going to lie and claim that the M is ideal for tracking kids running around. Neither is the iPhone, most P&S bodies, or a lot of mirrorless bodies. Kids can be as challenging as sports so grab a sports orientated DSLR for kids.
When kids are sitting down and being cute, I see no reason why you can't anticipate and capture the peak moment with the M. If I can do it with a street drummer....
2) Some event/occurance you saw while driving or stopped at light (as a passenger of course) that you want to record instantly.
You have a lot of those that are over and done with in the time it takes the M to AF? I know there's a lag, but come on....
Don't get fixated on pixel density and fps and all and swear that you would never touch iPhone. There will be time when it will be faster (note faster is not equal to better) for you to whip iPhone to take a shot while accessing M, switching on and fumbling with its quirks will actually miss the moment.
Playing right now at my desk...my iPhone has more AF/release lag then my M. On the M I'm using single point AF with the 22mm f/2. Haven't even really tried the others. Perhaps you're seeing more lag with the other modes?