A clarification on this:
An esc with higher current capability normally has lower resistance mosfets or more mosfets in parallel and that equals a lower total resistance - in this regard the losses in the esc are actually lower with a higher current esc.
Regarding the switching losses, this is caused in the regulation of the voltage by PWM and switching mosfets. In theory the most efficient is to have no switching losses, (mosfets are run in ON mode all the time) but this (almost) never happens as motors aren’t run in full throttle and full speed for any longer amount of time.
In reality the switching losses aren’t large even if you compare two different drive voltages.
You’ll find better possibilities to get higher efficiency with 1) having a motor and propeller that is running in their optimal efficiency range and 2) having enough battery to decrease resistance losses in the battery.
A 21ah pack of 14s7p 30q cells, internal resistance is 14x30/7 so 60mohm
65161 motor has somewhere around 30-50mohm internal phase resistance depending on kV - so losses are higher in battery than in the motor in the example.
An esc with good mosfets in comparison can have a fraction of the above. The apd200f3x states 0.55mohm resistance, that’s more than 100 times lower than the battery losses. At switching the esc losses are a tiny bit higher - but still small in comparison.
I found this: https://www.ti.com/lit/an/slyt664/slyt664.pdf?ts=1680687865972
That has a simple figure for the switch mosfet losses:
Note that the switching losses are frequency related and that the diagram starts at 100kHz whereas a normal ESC switching is 16-20kHz.
Way back i had an excel sheet from either rcgroups or endless sphere that calculated total losses at different duty cycles. Can’t seem to find it now unfortunately.