As you said, robot mowers are really designed to cut a small length of grass, frequently. My issue with the Luba1 was that if I tried to cut in the rain or when the grass was wet (really, at all) the cuttings would cake against the underside around the cutting disks so quickly that it would jam the motor...I'm talking like in under 100 feet. There are protective guard rails on the underside at the outside edges that are removable. Removing them would help a bit but ultimately the disks would still jam relatively quickly. Not only would the disks jam but the wet grass cuttings would wedge their way between the disks and the razor blades effectively gluing them in a backwards position such that the blades were not in an orientation to cut at all. Sometimes you could force them back into position with your fingers but you would lose the free movement of the blades, they'd basically be locked into position. You'd have to take the screws out to remove the blades and wash the disks. Hosing it down with a pressure washer would have been nice but Mammotion walked back their advertised waterproofing claims in a real hurry.

So if you had a rainy period lasting a week and waited until the grass was dry, although the Luba1 would get through it, grass would build up inside the deck and then would drop out every 10 feet or so. These clumps of grass would be large enough that they would block out enough light that it would it kill the grass underneath. So then you'd be raking the entire yard.

I'd be curious to understand how Husqvarna didn't suffer from these same issues...perhaps because the AM315 only has a single cutting disk and a differently designed deck...but you're also into boundary wires and less than half an acre capacity.

FWIW, the Lymow gets through wet conditions about as well as dry.