I talked to someone with a WOZ on route and he said it was on pace to break even in about 2-3 years. That's with a 50/50 split I think. Not sure if that's normal, but for an Op that seems long to me to make it a business, but then again like someone said earlier, if you've got some $2000 machines in play, they get a lot of play too and that breakeven ROI is much shorter.
I also hear that machines like Simpsons always do well on location b/c of the theme - they attract lots of people who just think it looks fun vs. us pinheads who might play more of the Top 100 type games vs a theme that might appeal to families and kids...