Obviously everyone's business is their own, but I don't get charging $400 or $500 a month to rent a pinball machine. You wouldn't normally make that much money off a pin after splitting with the location, would you? And machines on location can get broken or damaged just as easily as ones at home. Besides, speaking for myself, any pin in my house gets taken care of much better than any at a bar or traditional arcade.
Have you seen the way some non-pinheads play sometimes? I've literally seen kids and "special" people slam the flippers bam,bam,bam,bam nonstop until the ball drains, and then bam,bam,bam,bam until ball 2 drains, and then bam,bam,bam,bam continually until ball 3 drains. Makes me cringe everytime it happens. I'm honestly surprised that you don't get more blown flipper coils from location pins.
But anyway, I think a short interview with the prospective renter could weed out people unsuited to having your games in their house, and you could charge a deposit if you were worried about any damage. It seems like some operators are thinking they'd get calls all the time to come over and fix things. I just don't think that's what would actually happen. Surely the only people interested in pin rentals are actual pinheads that wouldn't break stuff, and that would know how to take off the glass to remove a stuck ball.
Obviously, operators have to do what they're comfortable with. I just don't understand why having a pin in a responsible pinheads house is any more of a risk than having it in a bar or arcade, or why/how it would be any more of a maintenance problem. But that's just my thinking. I'm of the "rent out pins to make a little money while they're sitting idle" mindset.