Just from a glance at the microcontroller datasheets, it looks like the RA4M1's current draw in "Software Standby" mode is much lower than the older ATmega328P's "power down" mode (5μA vs. ~50μA).
But IIRC, the voltage regulators in previous Arduino boards already waste orders of magnitude more current than that, even while quiescent, making them not very suitable for battery-powered applications. So it remains to be seen if the R4 board improves on this.
But IIRC, the voltage regulators in previous Arduino boards already waste orders of magnitude more current than that, even while quiescent, making them not very suitable for battery-powered applications. So it remains to be seen if the R4 board improves on this.