Cordless mowers for large/challenging lawns - are they any good yet?

This is what my life has become - shoot me now.

My second secondhand petrol mower has lunched itself. I have to admit to myself that I'm just wasting my time and money and buying new is a regrettable next step.

Spec

• Needs a big deck - current 51cm on the outgoing petrol jobbie is a good size and I'd be reluctant to go smaller.
• Needs to be robust - my lawn is laughably called a garden if you squint in the right direction but it has aspects of field, hints of woods, with more than an aftertaste of moss.
• Did I say it had moss? I've slept on less comfy mattresses and if you stand still long enough and your feet sink without trace. There's a petrol scarifier waiting the kick the shit out of it once I've got it back in hand.
• It's not flat. At all.
• It needs to be self propelled. I'm old and it's lumpy.
• Garden is 'only' 800m2 but it's a bastard odd shape. 

I'm mildly cordless leccy mower curious. Maybe better for my tinnitus, one less bastard carburettor to clean, slightly quieter to not annoy the paying guests in the self catering that keep me in food and water. Possibly more eco - maybe. 

Has anyone gone leccy (not a robot - even the guy that sells robots thought it would be a challenge) with a garden other than a bowling green? If so what was it and has it worked?

ta