It depends on the timing requirements of your application. Ongoing flash operations will delay servicing of interrupts. The SD flash API should be used if you want to write to flash while using one of the softdevice stacks to ensure that the flash operation doesn't cause the the timing requirements of the stack to be exceeded. I'd recommend to use the pstorage module If you're using a softdevice.
It depends on the timing requirements of your application. Ongoing flash operations will delay servicing of interrupts. The SD flash API should be used if you want to write to flash while using one of the softdevice stacks to ensure that the flash operation doesn't cause the the timing requirements of the stack to be exceeded. I'd recommend to use the pstorage module If you're using a softdevice.
