Un-wired Robotic lawn mower

I've got about 1/4 acre with some odd shapes and walkways. I'm looking to invest in a robotic mower, but the boundary wire ones don't seem to work with my layout. It doesn't need to have clean mow lines or anything, I just want my grass to be shorter.

Does anyone have any recommendations for a non-wired robot mower? Preferably one that integrates with HA, but that's not required.

If you do, what are the pros/cons of the unit?