I've done a couple of versions of robotic mowers (Robomow and Worx, primarily). For a smaller yard that is reasonably flat and obstruction free, they'd be the bomb. My problem is that I worked them waaaay past a realistic duty-cycle and they just couldn't keep up.
The Worx unit covered the small area that I am looking at getting an electric mower for (to replace my Honda self propelled, which by the way, has been a great mower imo) well enough, but its biggest problem is that it uses 5 razor blades attached to a hub for cutting. I know they do that because the weight of an actual mower blade would be too much for the motor/battery, but it just doesn't really cut all that well and the blades don't hold up very well. Battery life wasn't a problem as it was a small work area and it was pretty reliable as far as cycling, finding and docking in its station to recharge, etc. It just couldn't cut it, so to speak.
The Robomow units (I had two of them to try and maintain roughly 1.75 acres of mowing) had a decent mowing blade and were pretty reliable all in all, but my terrain was just too much for them and they were working themselves to death. I don't want to get into replacing $500 batteries on two mowers each year, and there were some other parts, including logic boards that I had to replace as well, and it just didn't have the "big manufacturer" support that I think these require. Robomow itself was fine and worked to be helpful supporting me while I was using them but I truly needed something that hadn't quite hit the marketplace yet. Husqvarna had a somewhat tempting unit hit the market after I had already committed to Robomow, but I don't think those were quite *there* yet either, so I am waiting for a generation or two of improvement before I jump back into robotic mowing, although I am a big fan of it.
Apologies to the OP, I will quit derailing your thread now. If anyone wants to talk robotic mowing, let me know and I'll start a separate thread.