do you currently have any other battery powered systems or are you also looking for battery powered everything?
i love my ryobi battery powered mower
imo, have double the battery power available or waiting to charge, why? battery powered mowers are "on demand" if your going over a thick patch or you forgot to mow, they will kick it up and of course use more power.
still, it's so much i don't have to worry about, the ease of use
i'm pretty sure i got this one or something close to it (ryobi changes models a lot)
my total yardage is 4700sq/ft, it'll take me 1 full battery and 10-15minutes of the 2nd battery.
i have needed to use both batteries to dead a few times in the fall, i don't blow my leaves, i just mow em, and that takes a lot of battery, it drains the batteries depending on how much was shed.
i can give you more info about my experiences, but using an electric over a gas will still translate, i would absolutely always use the battery powered, i've had corded and awd gas, would never go back.
the ego's seem to have more "quality of life" improvements, honestly if i wasn't already tied into ryobi i'd probably get an ego mower and ego outdoor system.
b/c you might not just be buying an eco mower, you'll be buying an ecosystem to work w/ the batteries.