Just bringing this back up.
I finally got round to using my $799 - 5AH, mulching, 46cm width one. My section is flat and has about 320sqm of lawn.
Took me just a shade over an hour to mow the lawn and i still had a 1 bar of battery left when i finished. i was rather impressed to be honest. there was a little bit of long grass in there and you can hear the motor change pitch when it hits that stuff but didn't struggle at all.
First impressions were, man its quiet, and you can tell it doesn't have as much power as there is no where near the dust or debris being emitted from under it. it was slightly narrower than my old petrol mower so in some places i had to do an extra pass but thats not a huge deal. Its also light, so pretty easy to manouver, but it is longer by a little which can be a little annoying.
Fast charger has the battery charged in about 75 minutes which is good, but i do have a spare.
all in all its a pretty good mower, the missus even had a go with it to mow under the tramp while i held it up for her. she liked it too.