In my opinion, OVERLAYS are only good for machines that would be home use only with small to medium game numbers being played.
Something alot of people dont realise, is that alot of commercial sellers use overlays and never say anything. If its done right, its hard to tell, until you rub your fingers accross the playfield and feel the ridge of the sticker.
Interestingly, there was a INDIANNA JONES WIDEBODY that sold apx 10 days ago on Ebay for $3300. When i closely looked at the feedback for the seller, i could see that they had purchased a Indy Overlay a few weeks before from a melb parts seller. Thats why the machine was so cheap. Wonder if the buyer put 2 and 2 together. ?