Earlier quoted context omitted.
I think the vast majority of these iot applications are something like “read; send; sleep 60”. But your point stands that people needing high precision and timing probably won’t reach for this.
That's the point of having the M4 cores alongside the M7 though, isn't it? Let the M4's handle real-time stuff like driving motors, and the M7 do communication and/or user interface.
If it's two totally independent cores with totally independent sets of devices, how do you manage the pinmux? Are there independent pinmuxes?
And finally is the M4 core capable of detecting single-faults in the cache, memory, flash registers, and instruction pipeline? Such as might be caused by cosmic rays?
These are some things I would look for if I was specifying a processor pair for use in a safety-critical system.